LINAC2014 - List of Keywords (electron)

Paper	Title	Other Keywords	Page
MOIOB02	Optimizing RF Linacs as Drivers for Inverse Compton Sources: the ELI-NP Case	emittance, linac, laser, photon	16
	C. Vaccarezza, D. Alesini, M. Bellaveglia, R. Boni, E. Chiadroni, G. Di Pirro, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, B. Spataro, P. Tomassini INFN/LNF, Frascati (Roma), Italy A. Bacci, D.T. Palmer, V. Petrillo, A.R. Rossi, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy I.V. Drebot Universita' degli Studi di Milano e INFN, Milano, Italy A. Giribono, A. Mostacci, L. Palumbo Rome University La Sapienza, Roma, Italy C. Ronsivalle ENEA C.R. Frascati, Frascati (Roma), Italy
	The design guide-lines of RF Linacs to fulfill the requirements of high spectral density Inverse Compton Sources for the photo-nuclear science are mostly mutuated from the expertise coming from high brightness electron Linacs driving X-ray FEL's. The main difference is the quest for maximum phase space density (instead of peak brightness), but many common issues and techniques are exploited, in order to achieve an optimum design and lay-out for the machine. A relevant example in this field is the design of the hybrid C-band multi-bunch RF Linacs for the ELI-NP Gamma Beam System, aiming at improving by two orders of magnitude the present state of the art in spectral density available for the gamma-ray beam produced.
	Slides MOIOB02 [2.542 MB]

MOIOB03	Generation and Acceleration of Low-Emittance, High-Current Electron Beams for SuperKEKB	emittance, gun, laser, wakefield	21
	M. Yoshida, N. Iida, S. Kazama, T. Natsui, Y. Ogawa, S. Ohsawa, L. Zang, X. Zhou KEK, Ibaraki, Japan
	KEK e⁻/e⁺ linac is now in a final stage of upgrade for SuperKEKB. One of the key issues is to stably generate and accelerate a low-emittance, high charge electron beam for SuperKEKB (a couple of single-bunched beams with a charge of 5 nC and a normalized emittance of 20 mm-mmrad each).
	Slides MOIOB03 [3.981 MB]

MOIOB04	Current Status of PAL-XFEL	undulator, gun, linac, experiment	26
	I.S. Ko, J.H. Han PAL, Pohang, Kyungbuk, Republic of Korea
	The PAL-XFEL project aims to produce 0.1~nm coherent X-ray laser to photon beam users. In order to produce such photons, there are 10 GeV electron linac based on S-band normal conducting accelerating structures and a 150 m long out-vacuum undulator system. The project was already started in April 2011, and the 1.1 km long building is expected to be completed by December 2014. The injector test facility (ITF) which is for a test of the first 139 MeV section of the main linac has been installed and is in normal operation at the extension of the PLS linac building. In this paper, we introduce the project in general, a brief summary of site preparation and building construction, beam test results of ITF, and test results of subsystems produced by domestic manufacturers
	Slides MOIOB04 [9.901 MB]

MOIOC01	Status of Superconducting Electron Linac Driver for Rare Ion Beam Production at TRIUMF	cavity, cryomodule, linac, TRIUMF	31
	R.E. Laxdal, F. Ames, R.A. Baartman, I.V. Bylinskii, Y.-C. Chao, D. Dale, K. Fong, E.R. Guetre, P. Kolb, S.R. Koscielniak, A. Koveshnikov, M.P. Laverty, Y. Ma, M. Marchetto, L. Merminga, A.K. Mitra, N. Muller, R.R. Nagimov, T. Planche, W.R. Rawnsley, V.A. Verzilov, Z.Y. Yao, Q. Zheng, V. Zvyagintsev TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	A MW class cw superconducting electron linac is being installed at TRIUMF as a driver for radioactive beam production through photo-fission. The ARIEL e-linac will house five 1.3GHz nine-cell cavities in three cryomodules and accelerate up to 10mA of electrons to 50MeV. A first phase of installation will see three cavities in two cryomodules installed by the end of 2014. Presently the injector cryomodule is installed and undergoing cryogenic and rf characterizations and beam acceleration tests with beam from the 300kV DC gun. The second cryomodule is being prepared for first tests. The linac status including descriptions and operating performance of installed cryogenic and rf systems, electron gun performance, cryomodule performance and the results of first beam acceleration tests will be reported.
	Slides MOIOC01 [6.383 MB]

MOPP002	Design of a Superconducting Quarter-Wave Resonator for eRHIC	cavity, linac, SRF, niobium	49
	S.V. Kutsaev, Z.A. Conway, M.P. Kelly, B. Mustapha, P.N. Ostroumov ANL, Argonne, USA S.A. Belomestnykh, I. Ben-Zvi Stony Brook University, Stony Brook, USA S.A. Belomestnykh, I. Ben-Zvi, Q. Wu, W. Xu BNL, Upton, Long Island, New York, USA B. P. Xiao SBU, Stony Brook, New York, USA
	Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 and by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 The electron-ion collider project (eRHIC) at Brookhaven National Laboratory requires a 50 mA 12 MeV electron injector linac for eRHIC main linac and an SRF electron gun for a Coherent electron Cooling (CeC) linac. The necessity to deal with long electron bunches required for both the eRHIC injector and the coherent electron cooler sets the frequency requirement of 84.5 MHz. Quarter wave resonator is a perfect choice for this frequency because of its dimensions, RF parameters and good experience with manufacturing and using them at ANL. Here we present the design and optimization of an 84.5 MHz 2.5 MV superconducting quarter-wave cavity suitable for both machines. One such QWR will be used as a bunching cavity in the injector linac, the other one as the photoemission electron source for the CeC linac. In addition to the optimization of the QWR electromagnetic design we will discuss the tuner design, approaches to cavity fabrication and processing.

MOPP004	Design and Development of Pulsed Modulators for RF Electron Linacs	linac, klystron, gun, operation	55
	K.P. Dixit, S. Chandan, N. Chaudhary, R.B. Chavan, L.M. Gantayet, S.R. Ghodke, M. Kumar, K.C. Mittal, H.E. Sarukte, A.R. Tillu, H. Tyagi, V. Yadav BARC, Mumbai, India
	Pulsed Modulators required for RF sources, based on klystrons and magnetrons, for RF electron linacs have been designed and developed at Electron Beam Centre, BARC, Mumbai, India. Electron guns in these linacs have also been powered by pulsed modulators. Line-type modulators, as well as IGBT-based solid-state modulators have been developed for these applications. A 150 kV/100 A line-type modulator has been tested on klystron to generate 7 MW peak RF Power. Magnetron modulator has undergone testing up to 40 kV, 165 A on resistive load. Solid-state modulator, using fractional-turn pulse transformer has been designed, developed and tested successfully on magnetron load up to output power of 1.3 MW peak. A transformerless solid-state modulator for electron gun of 6 MeV cargo-scanning linac, uses the Marx adder configuration and has been successfully tested up to 40 kV. In addition, line-type modulators for electron guns up to 85 kV have been successfully commissioned and are in operation in the linac systems. This paper describes the salient design features of these modulators, development of pulse transformers, details of test set-up and discusses the test results of these modulators.
	Poster MOPP004 [2.343 MB]

MOPP005	High Power Electron Accelerator Programme at BARC	linac, neutron, experiment, acceleration	58
	K.C. Mittal, S. Acharya, R.I. Bakhtsingh, R. Barnwal, D. Bhattacharjee, S. Chandan, N. Chaudhary, R.B. Chavan, S.P. Dewangan, K.P. Dixit, S. Gade, L.M. Gantayet, S.R. Ghodke, S. Gond, D. Jayaprakash, M. Kumar, M.K. Kumar, H.K. Manjunatha, R.L. Mishra, J. Mondal, B. Nayak, S. Nayak, V.T. Nimje, S. Parashar, R. Patel, R.N. Rajan, P.C. Saroj, H.E. Sarukte, D.K. Sharma, V. Sharma, S.K. Srivasatava, N.T. Thakur, A.R. Tillu, R. Tiwari, H. Tyagi, A. Waghmare, V. Yadav BARC, Mumbai, India
	Bhabha Atomic Research Centre in India has taken up the indigenous design & development of high power electron accelerators for industrial, research and cargo-scanning applications. For this purpose, Electron Beam Centre (EBC) has been set up at Navi Mumbai, India. Pulsed RF Linacs, with on-axis coupled cavity configuration, include the 10 MeV Industrial RF linac, as well as 9 MeV linac and compact 6 MeV linac for cargo-scanning applications. Industrial DC accelerators include a 500 keV Cockroft-Walton machine and 3 MeV Dynamitron. Several radiation processing applications, such as material modification, food preservation, flue-gas treatment, etc. have been demonstrated using these accelerators. Cargo-scanning linacs have been successfully commissioned and are being characterized for the required x-ray output. A 30 MeV RF Linac, for research applications, such as shielding studies and n-ToF experiments, is being designed and developed. For ADS studies, a 100 MeV, 100 kW RF Linac system is proposed. This paper presents the details of the design of these accelerators, their development, current status and utilization for various applications.

MOPP007	SF6 Gas Monitoring and Safety for DC Electron Beam Accelerator at EBC, Kharghar, Navi Mumbai	monitoring, high-voltage, operation, experiment	61
	S.K. Suneet, S. Acharya, S. Banerjee, R. Barnwal, D. Bhattacharjee, N. Chaudhary, R.B. Chavan, K.P. Dixit, S. Gade, L.M. Gantayet, S.R. Ghodke, S. Gond, B.S. Israel, D. Jayaprakash, N. Lawangare, K. Mahender, R.L. Mishra, K.C. Mittal, B. Nayak, S. Nayak, R. Patel, R.N. Rajan, P.C. Saroj, D.K. Sharma, V. Sharma, M.K. Srvastava, D.P. Suryaprakash, N.T. Thakur, R. Tiwari, A. Waghmare BARC, Mumbai, India
	A 3 MeV, 30kW DC Industrial electron beam accelerator has been designed, commissioned and tested at Electron beam centre, Kharghar. The accelerator has been tested upto 5 kW power level with SF6 gas at 6 kg/cm². The accelerating column, high voltage multiplier column, electron gun and its power supply are housed in accelerator tank, which is filled with SF6 gas as gaseous insulator at 6 kg/cm². The SF6 gas is being used due to high dielectric strength and excellent heat transfer characteristics. The SF6 gas is non toxic and non carcinogenic. The SF6 gas replaces oxygen hence the TLV (threshold limiting value) is 1000 ppm for inhaled gas for persons working on the SF6 gas handling system. The SF6 gas is being green house gas, leak tightness has to monitor in the system and leak if any should be repaired. The gas should be used, recycled and reuse and thus saving the environment. This paper describes the safety and monitoring of the SF6 gas leak, quality and precautions in 3MeV accelerator.
	Poster MOPP007 [1.389 MB]

MOPP010	Low Charge State Laser Ion Source for the EBIS Injector	ion, injection, laser, target	64
	M. Okamura, J.G. Alessi, E.N. Beebe, T. Kanesue, C.J. Liaw, V. LoDestro, A.I. Pikin, D. Raparia, J. Ritter BNL, Upton, Long Island, New York, USA Y. Fuwa, S. Ikeda, M. Kumaki RIKEN, Saitama, Japan
	Funding: NASA In March 2014, we have successfully commissioned a newly designed low charge high brightness laser ion source (LIS) which delivers various singly charged heavy ions to the electron beam ion source (EBIS) at Brookhaven National Laboratory. Now the LIS is used at routine operation of the RHIC-AGS accelerator complex and is providing stable less-contaminated beams. The laser power density was optimized to provide singly charged ions with low material consumption rate. The nominal laser energy on the target is around 500 mJ with 1064 nm Nd:YAG of the wave length. The induced plasma by the laser is transported through a 3 m pipe to stretch ion beam pulse length to match the EBIS’s requirement and the degradation of the beam current caused by the long drift section of the pipe can be compensated by a longitudinal magnetic filed induced by a coil surrounding the pipe. We also employed a twin laser system to extend the beam width further. At the conference, we will discuss the effect of the new LIS on the various accelerated beams through the EBIS, RFQ and IH-linac.

MOPP012	Beam Commissioning of the SRF 704 MHz Photoemission Gun	cathode, gun, SRF, cavity	70
	W. Xu, S.A. Belomestnykh, I. Ben-Zvi, D.M. Gassner, H. Hahn, J.P. Jamilkowski, P. Kankiya, D. Kayran, N. Laloudakis, R.F. Lambiase, G.T. McIntyre, D. Phillips, V. Ptitsyn, K.S. Smith, R. Than, D. Weiss, A. Zaltsman BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi, V. Ptitsyn Stony Brook University, Stony Brook, USA D. Holmes AES, Medford, New York, USA
	Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. A 704 MHz superconducting RF photoemission electron gun for the R&D ERL project is under comissioning at BNL. Without a cathode insert, the SRF gun achieved its design goal: an accelerating voltage of 2 MV in CW mode. During commissioning with a copper cathode insert it reached 1.9 MV with 18% duty factor, which is limited by mulitpacting in a choke-joint cathode stalk. A new cathode stalk has been designed to eliminate multipacting in the choke-joint. This paper presents recent commissioning results, including cavity commissioning without the cathode stalk insert, first beam commissioning of the SRF gun in pulsed regime, and the design of a multipacting-free cathode stalk.

MOPP013	Vertical Test Results of 704 MHz BNL3 SRF Cavities	cavity, HOM, SRF, damping	73
	W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn, R. Porgueddu, R. Than, D. Weiss BNL, Upton, Long Island, New York, USA S.A. Belomestnykh, I. Ben-Zvi Stony Brook University, Stony Brook, USA C.H. Boulware, T.L. Grimm Niowave, Inc., Lansing, Michigan, USA M.D. Cole, D. Holmes, T. Schultheiss AES, Medford, New York, USA
	Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE, and Award No. DE-SC0002496 to Stony Brook University with the U.S. DOE. An electron-ion collider (eRHIC) proposed at BNL requires superconducting RF cavities able to support high average beam current. A 5-cell niobium SRF cavity, called BNL3, was designed for a conventional lattice eRHIC design. To avoid inducing emittance degradation and beam-break-up (BBU), the BNL3 cavity was optimized to damp all dangerous higher-order-modes (HOMs) by employing a large beam pipes and coaxial antenna-type couplers. Additionally, the cavity was designed for an acceptable cryogenic load and peak surface RF fields. Two BNL3 cavities have been fabricated and tested at a vertical test facility at BNL. This paper addresses development of the SRF cavities for eRHIC, including SRF cavity design, fabrication and test results.

MOPP015	High Energy Electron Radiography Experiment Research Based on Picosecond Pulse-width Bunch	experiment, linac, proton, quadrupole	76
	Q.T. Zhao, S. Cao, R. Cheng, X.K. Shen, Z.M. Zhang, Y.T. Zhao IMP, Lanzhou, People's Republic of China Y.-C. Du TUB, Beijing, People's Republic of China W. Gai ANL, Argonne, Illinois, USA
	A new scheme is proposed that high energy electron beam as a probe is used for time resolved imaging measurement of high energy density materials, especially for high energy density matter and inertial confinement fusion. The first picosecond pulse-width electron radiography experiment was achieved by Institute of Modern Physics, Chinese Academy of Sciences and Tinghua University (THU), based on THU Linear electron accelerator (LINAC). It is used for principle test and certifying that this kind of LINAC with ultra-short pulse electron bunch can be used for electron radiography. The experiment results, such as magnifying factor and the imaging distortion, are consistent with the beam optical theory well. The 2.5 um RMS spatial resolution has been gotten with magnifying factor 46, with no optimization the imaging lens section. It is found that in the certain range of magnifying factor, the RMS spatial resolution will get better with bigger magnifying factor. The details of experiment set up, results, analysis and discussions are presented here.
	Poster MOPP015 [2.866 MB]

MOPP016	Extracting Superconducting Parameters from Surface Resistivity by Using Inside Temperature of SRF Cavities	cavity, accelerating-gradient, SRF, superconductivity	80
	G.M. Ge, G.H. Hoffstaetter, M. Liepe, H. Padamsee, V.D. Shemelin Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The surface resistance of an RF superconductor depends on the surface temperature, the residual resistance and various superconductor parameters. These parameters can be determined by measuring the quality factor of a SRF cavity in helium-baths of different temperatures. The surface resistance can be computed from Q0 for any cavity geometry, however it is less simple to determine the temperature of the surface when only the temperature of the helium bath is known. Traditionally, it was approximated that the surface temperature on the inner surface of the cavity is the same as the temperature of the bath. This is a good approximation at small RF-field losses on the surface, but to determine the field dependence of Rs, one cannot be restricted to small field losses. Here we show how computer simulations can be used to determine the inside temperature so that Rs(Tin) can then be used to extract superconductor parameters. The computer code combines the well-known programs HEAT and SRIMP. We find that the error of the incorrect fitting method is about 10% at high RF-fields.

MOPP019	Nb3Sn Materials Studies	niobium, SRF, cavity, ion	92
	S. Posen, M. Liepe Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA Th. Proslier ANL, Argonne, Illinois, USA
	Nb₃Sn is a very promising material for use in SRF cavity applications, potentially offering significant improvements in quality factor and energy gradient compared to niobium. In order to better understand how to optimize this material for SRF applications, Nb₃Sn samples were prepared at Cornell via vapor deposition, using varying parameters in the coating process. Microscopic studies were performed with SEM/EDX, and studies were performed on bulk samples to measure secondary electron yield, energy gap, and upper critical magnetic field. The results are presented here, with discussion for how they might point the way towards reaching even higher fields in Nb₃Sn cavities.
	Poster MOPP019 [2.742 MB]

MOPP024	Perspectives of the S-Band Linac of FERMI	operation, linac, klystron, FEL	105
	A. Fabris, P. Delgiusto, M. Milloch, C. Serpico Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy A. Grudiev CERN, Geneva, Switzerland
	The S-band linac of FERMI, the seeded Free Electron Laser (FEL) located at the Elettra laboratory in Trieste, has reached the peak on-crest electron energy of 1.55 GeV required for FEL-2 with the present layout. Different ways are being considered to extend the operating energy of the S-band linac up to 1.8 GeV. At the same time upgrades on the existing systems are investigated to address the requirements of operability of a users facility. This paper provides an overview of the developments that are under consideration and discusses the requirements and constraints for their implementation.

MOPP025	Longitudinal Beam Profile Measurements in Linac4 Commissioning	rfq, cavity, linac, emittance	108
	G. Bellodi, V.A. Dimov, J.-B. Lallement, A.M. Lombardi, U. Raich, F. Roncarolo, F. Zocca CERN, Geneva, Switzerland M. Yarmohammadi Satri IPM, Tehran, Iran
	Linac4, the future 160 MeV H⁻ injector to the CERN Proton Synchrotron Booster, is presently under construction at CERN as a central step of the planned upgrade of the LHC injectors. The Linac front-end, composed of a 45 keV ion source, a Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) and a Medium Energy Beam Transport (MEBT) housing a beam chopper, has been installed and commissioned. Precise measurements of the longitudinalμbunch profiles of ion beams were possible with the help of a Bunch Shape Monitor (BSM) developed at INR Moscow. These were crucial for the successful commissioning of the three RF buncher cavities mounted along the MEBT and well complemented with higher precision the information provided in parallel by spectrometer measurements.

MOPP030	CALIFES: A Multi-Purpose Electron Beam for Accelerator Technology Tests	wakefield, acceleration, quadrupole, laser	121
	J.L. Navarro Quirante, R. Corsini, W. Farabolini, D. Gamba, A. Grudiev, M.A. Khan, T. Lefèvre, S. Mazzoni, R. Pan, F. Peauger, F. Tecker, N. Vitoratou, K. Yaqub CERN, Geneva, Switzerland W. Farabolini, F. Peauger CEA/DSM/IRFU, France D. Gamba JAI, Oxford, United Kingdom M.A. Khan, K. Yaqub PINSTECH, Islamabad, Pakistan J. Ögren, R.J.M.Y. Ruber Uppsala University, Uppsala, Sweden N. Vitoratou Thessaloniki University, Thessaloniki, Greece
	The Compact Linear Collider (CLIC) project aims to accelerate and collide electrons and positrons up to 3 TeV center-of-mass energy using a novel two-beam acceleration concept. To prove the feasibility of this technology the CLIC Test Facility CTF3 has been operated during the last years. CALIFES (Concept d’Accélérateur Linéaire pour Faisceau d’Electron Sonde) is an electron linac hosted in the CTF3 complex, which provides a flexible electron beam and the necessary equipment to probe both the two-beam acceleration concept and novel instrumentation to be used in the future CLIC collider. In this paper we describe the CALIFES Linac and its beam characteristics, present recent test results, outline its future program on two-beam module testing and finally discuss about possible future applications as a multi-purpose accelerator technology test facility.

MOPP058	Z-slicer: A Simple Scheme for Electron Beam Current Profile Shaping in a Linac	laser, radiation, dipole, cavity	183
	J.C.T. Thangaraj, C.M. Baffes, D.R. Broemmelsiek, D.J. Crawford, R.M. Thurman-Keup Fermilab, Batavia, Illinois, USA W.B. Wortley University of Rochester, Rochester, New York, USA
	Short bunches are a premium at accelerator facilities and their applications include THz generation, short bunch production, shaped bunch production, etc. In this work we report on the design of an experiment involving an electron beam about 50 MeV that will be intercepted by a set of metallic slits inside a bunch compressor. After the mask, some electrons are scattered while other pass through un-affected. After exiting the bunch compressor, those electrons that were not affected by the slits will appear as short electron bunches. The key advantage of our scheme is its simplicity, tunability and low cost. The scheme does not require any additional hardware such as lasers, undulator, transverse deflecting cavity. The tuning variable is only the RF-chirp and detection of the bunching requires just a skew quad in the chicane and a transverse screen downstream. A thermal analysis suggests that MHz operation of the linac can be sustained under certain beam conditions without any damage to the slit mask.

MOPP065	Investigations of Space-Charge Compensation in Low-Energy Beam Transport (LEBT) Sections Using a Particle-in-Cell Code	ion, simulation, proton, space-charge	205
	D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner IAP, Frankfurt am Main, Germany
	Among the advantages of magnetostatic LEBT sections is the possibility for compensation of space charge by electrons in the case of positively charged ion beams. In the past, it has been shown that the distribution of these compensation electrons can lead to unwanted emittance growth. However, the distribution of electrons especially in the presence of the magnetic fields of the focussing lenses is difficult to predict. To improve the understanding of the influence on the beam, models for the relevant processes namely residual gas ionization using realistic cross sections as well as secondary electron production on surfaces have been implemented in a particle-in-cell code. In this contribution, we will present the code used as well as first results for two model systems as an example.

MOPP077	Electron-Driven Positron Capture Simulation for ILC	positron, target, linac, booster	233
	Y. Seimiya, M. Kuriki HU/AdSM, Higashi-Hiroshima, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan T. Okugi, T. Omori, M. Satoh, J. Urakawa KEK, Ibaraki, Japan T. Takahashi Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
	ILC (International Linear Collider) is a next high-energy physics project to study the Higgs property as detail as possible and new phenomena beyond standard model. In ILC, the positron beam is produced by converting gamma rays from undulator radiations. To obtain gamma rays as undulator radiation, the electron beam for collision (150 GeV or more) is used. This positron generation scheme is a totally new approach. From project point of view, it is desirable to have a technical backup as a replacement of the undulator scheme. We propose an ILC positron source based on the conventional electron driven scheme. In this scheme, positron beam is generated from electromagnetic shower in a heavy target material where electron beam is injected. By manipulating the beam time structure to relax the heat load on the production target, the scheme can be feasible technically. In this study, positron capture in the electron driven scheme is simulated from the positron production to the positron damping ring, to demonstrate that an enough amount of positron can be generated and captured with a controllable heat load on the target.
	Poster MOPP077 [0.879 MB]

MOPP083	Helical Waveguides for Short Wavelength Accelerators and RF Undulators	undulator, FEL, focusing, radiation	248
	S.V. Kuzikov, A.V. Savilov, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia A.V. Savilov NNGU, Nizhny Novgorod, Russia
	The short wavelength accelerating structure can combine properties of a linear accelerator and a damping ring simultaneously. It provides acceleration of straight on-axis beam as well as cooling of this beam due to the synchrotron radiation of particles. These properties are provided by specific slow eigen mode which consists of two partial waves, TM01 and TM11. The flying RF undulator introduces a high-power short pulse, propagating in a long helically corrugated waveguide where the -1st space harmonic with negative phase velocity is responsible for particle wiggling. High group velocity allows providing long interaction of particles with RF pulse. Calculations show that RF undulator with period 5 mm, undulator parameter 0.1 is possible in 1 GW 10 ns pulse at frequency 30 GHz. The eigen mode in a helical undulator might have 0th harmonic phase velocity equal to light velocity. Such wave can be excited by relativistic drive bunch in the waveguide where witness bunch follows after the drive bunch, wiggles in wakefields, and generates X-rays at whole waveguide length. Helical waveguides can also be used in order to channel low-energy bunches in RF undulator of THz FEL.
	Poster MOPP083 [2.139 MB]

MOPP084	Nondestructive Diagnostics of Proton Beam Halo and Transverse Bunch Position by Cerenkov Slow Wave Structures	proton, simulation, diagnostics, monitoring	251
	S.V. Kuzikov, M.B. Goykhman, A.V. Gromov, A.V. Palitsin, Yu.V. Rodin, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia
	An appearance of the halo around bunch of particles is very undesirable destructive phenomenon in high-intensity proton accelerators. We suggest using built-in short BWO section in form of the corrugated metallic waveguide, in order to control particle distribution in real time. In BWO low velocity proton bunch has synchronism with slow spatial harmonic of TM01 wave. Fields of slow harmonic sharply grow in direction from axis to walls and rf power, generated by flying bunch of the given charge, critically depends on transverse bunch size. Results of the simulation, carried out for 20 pC proton bunch of 10 ps duration, show that in 5 GHz BWO of 30 cm length the output rf pulse of several nanosecond duration is varied from mW- level (for 1 mm transverse bunch size) to several tens of mW (for bunch of 20 mm radius). This power level is high enough to control halo appearance in each single proton bunch. The producible rf power in a BWO is also dependent on bunch deflection from axis. This effect we plan to use, in order to provide transverse bunch position monitoring by means of two additional rectangular slow wave section which have corrugations on mutually perpendicular walls.
	Poster MOPP084 [0.732 MB]

MOPP086	Ecr Ion Sources Developments at INFN-LNS for the Production of High Brightness Highly Charged Ion Beams	plasma, ion, ion-source, ECRIS	254
	D. Mascali, C. Altana, L. Andò, C. Caliri, G. Castro, L. Celona, S. Gammino, L. Neri, F.P. Romano, G. Torrisi INFN/LNS, Catania, Italy G. Sorbello University of Catania, Catania, Italy
	The design of future high-performing ECRIS will require alternative approaches in microwave-to-plasma coupling, in order to maximize the electron density at relatively low frequency and reduce the super-hot electrons formation and their consequences on the beam stability and on source reliability. On these purposes, different activities have been carried out at INFN-LNS in the recent past, including advanced modelling, diagnostics, and studies about alternative methods of plasma heating based on electrostatic-waves generation. A description of these activities will be presented, with special emphasis to the microwave to plasma coupling and to the plasma diagnostics. Some of the already collected results have been a basis for the design of the new AISHa source (for hadrontherapy purposes) and the construction of the innovative prototype named Flexible Plasma Trap: on this machine we will search for advanced schemes of microwave launching, now ongoing thanks to full-wave plus kinetic calculations of the wave-to-plasma interaction mechanism

MOPP093	Evaluation of Beam Energy Fluctuations Caused by Phase Noises	linac, experiment, timing, cavity	273
	H. Hanaki, H. Dewa, S. Suzuki, K. Yanagida JASRI/SPring-8, Hyogo-ken, Japan T. Asaka, T. Ohshima RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	The SSB noises of the RF reference signal dominate the short-term instabilities of the RF phase of the carrier RF. This phase modulation finally results in beam energy fluctuation. This presentation gives a quantitative evaluation of the beam energy fluctuations in an electron linear accelerator caused by phase noises, comparing a theoretical analysis and experimental results. A simple model was introduced to understand how phase noises result in the relative phase difference between a beam bunch and accelerating RF fields. In the experiments, we measured the enhanced beam energy fluctuations by modulating the phase of the reference RF signals with an external signal. The interference between the accelerating RF phase modulation and the timing modulation of a beam bunch was found in the model analysis and also in the experimental results.

MOPP094	Latest Improvements of the SPring-8 Linac for High Reliability	linac, operation, vacuum, injection	276
	S. Suzuki, H. Dewa, H. Hanaki, T. Kobayashi, T. Magome, A. Mizuno, T. Taniuchi, K. Yanagida JASRI/SPring-8, Hyogo-ken, Japan T. Asaka RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	In order to perform stable injection to the 8GeV SPring-8 storage ring, which is performing the top-up operation, the high reliability of the linac has been advanced as follows: For reduction of phase variations caused by the waveguide deformation due to the variations of temperature or atmospheric pressure, the waveguide circuit of SF6 enclosure type, which fed RF powers to the bunching section, was replaced with that of vacuum type. And S-band 10MW circulators and isolators of vacuum type were adopted for the first time in the world. The timing system was improved so that the interval time of the beam injection into the 8GeV booster synchrotron and the 1.5 GeV NewSUBARU storage ring has been reduced to 1 sec from 15 seconds, respectively, even in the top-up operation of both storage rings. As a result, the stored current by the top-up operation were further stabilized. The stored current of the NewSUBARU storage ring was stabilized to 0.18% from 0.31%. The electron gun cathode assembly has been developed to reduce the dark emission from a grid plate by the double grid method and the electrolytic polishing.

MOPP095	Emittance Measurement for SPring-8 Linac Using Four Six-Electrode BPMs	emittance, linac, quadrupole, focusing	279
	K. Yanagida, H. Hanaki, S. Suzuki JASRI/SPring-8, Hyogo-ken, Japan
	In the SPring-8 linear accelerator (linac) six-electrode beam position monitors (BPMs) have been installed to measure second-order moments. At the end of the linac where the electron beam energy is 1 GeV four quadrupole magnets are utilized for twiss parameter matching toward the following beam transport line. Last year four six-electrode BPMs were installed at the locations of these four quadrupole magnets for an emittance measurement. The relative second-order moments were obtained changing the magnetic field strength of the quadrupole magnets, then beam sizes, emittances and twiss parameters were deduced or calculated. At this time we applied one pair of beam sizes measured by the screen monitor for a precise determination of emittances but we try to implement non-destructive measurement with no screen monitor. Before the emittance measurement a calibration with fifth-order moment correction was carried out changing beam positions at the BPM locations using upstream steering magnets (the entire calibration).
	Slides MOPP095 [0.984 MB]

MOPP098	Physical Starting of the First and Second Section of Accelerator Linac-800	undulator, klystron, linac, gun	288
	V. Kobets, N. Balalykin, I.N. Meshkov, V. Minashkin, G. Shirkov JINR, Dubna, Moscow Region, Russia V. Shabratov JINR/VBLHEP, Moscow, Russia
	In the report discusses the modernization of linear electron accelerator MEA (Medium Energy Accelerator). The aim is to develop a set of MEAs based free-electron lasers, imposed a number of emission wavelengths from infrared to ultraviolet. In work presents the results of the physical starting of the first and second stations accelerating electron linear accelerator LINAC-800, as well as start infrared undulator. We discuss the work program for this accelerator.

MOPP109	Ion Beam Acceleration in Neutron Tube	target, ion, neutron, space-charge	310
	V.I. Rashchikov MEPhI, Moscow, Russia A.S. Plastun ITEP, Moscow, Russia
	Deuteron beam acceleration in ion-optic system of gas-filled neutron tubes was investigated. PIC code SUMA "" used for computer simulation of ionization and knock on processes and there influence on deuteron beam parameters. When deuteron and ionized particles own space charge forces become the same order of magnitude as external one, virtual cathode may occurs. It is happened because of injected from ion source deuterons cannot overcome their own space charge potential wall and move in transverse direction. However, electrons, produced by ionization, are trapped within the deuteron beam space charge potential wall and decrease it significantly. Thus, space charge neutralization of deuteron beams by electrons, may considerably increase target current and, as a result, output neutron flow. Moreover, own longitudinal electric field rise near the target leads to reduction of accelerating electrode – target potential wall, which was made to prevent knock on emission from the target. As a result, additional knocked on electrons may appear in the region and should be taken into account. The data obtained were compared with experimental results. A.N. Didenko, V.I. Rashchikov, V.E. Fortov, Technical Physics, Vol. 56, No. 10,pp. 1535–1538, 2011

MOPP110	Multipacting Prediction for the 10⁶.1 MHz Quarter Wave Resonator	simulation, cavity, ISAC, experiment	313
	M. Gusarova, I.I. Petrushina, E.A. Savin, A.N. Stolbikova MEPhI, Moscow, Russia V. Zvyagintsev TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	The results of analytical calculations and numerical simulations of multipacting in the 10⁶.1 MHz Quarter Wave Resonator (QWR) are presented. Resonant voltages, impact energies and corresponding particle trajectories are obtained. In this paper we compare CST PS and MultP-M 3D simulation results for multipacting in the cavity.

MOPP128	Bridging the Gap Between Conventional RF Acceleration and Laser Driven Acceleration	operation, experiment, acceleration, cyclotron	358
	M.V. Fazio, V.A. Dolgashev, S.G. Tantawi SLAC, Menlo Park, California, USA
	For decades conventional RF accelerators have been built and operated with ever increasing capability through a few tens of gigahertz in frequency. More recent research takes advantage of the continuing development of high peak power short pulse lasers to drive accelerator structures at optical frequencies. This jump from RF to optical frequencies skips four orders of magnitude in wavelength. With recent experiments that demonstrate high gradients in metallic structures at millimeter wavelengths one is compelled to consider the viability of new approaches for acceleration in the millimeter-wave to terahertz regime. This paper will explore some of these possibilities.

MOPP132	Development of a Micro-Pulse Electron Gun Based Upon pi-Mode Dual-Cavity	cavity, gun, cathode, simulation	367
	L. Liao, Q. Gu, M. Zhang, M.H. Zhao SINAP, Shanghai, People's Republic of China
	The concept of a novel micro-pulse electron gun (MPG) based upon pi-mode dual-cavity is proposed and analyzed in this paper, and we termed it as dual-cavity micro-pulse electron gun (D-MPG) as compared to single-cavity standard MPG. From simulations, it is clear that the D-MPG is capable of yielding dozens of ampere peak currents and a few ps bunch length. Thought the mechanism for dual cavity is not fully understand, the D-MPG has demonstrate the potential to be the injectors for FEL and THz radiation facilities. Also it is a good candidate to replace the thermal cathode for industrial and medical accelerator system because of the cost-effective of the D-MPG.

MOPP138	Fabrication and Measurements of 500 MHz Double Spoke Cavity	cavity, simulation, radiation, target	385
	H. Park, J.R. Delayen JLab, Newport News, Virginia, USA J.R. Delayen, C.S. Hopper, H. Park ODU, Norfolk, Virginia, USA
	The 500 MHz double spoke cavity has been designed for a high velocity application such as a compact electron accelerator at Center for Accelerator Science at Old Dominion University and is being built at Jefferson Lab. The geometry specific to the double spoke cavity requires a variety of tooling and fixtures. Also a number of joints are expected to make it difficult to maintain the geometric deviation from the design minimal. This paper will report the fabrication technique, resulting tolerance from the design, and comparison between the measurements and simulations.
	Poster MOPP138 [2.144 MB]

MOPP140	Simulations for the High Gradient, Low Emittance Supergun RF Photoinjector	emittance, coupling, simulation, gun	391
	A.D. Cahill, A. Fukasawa, J.B. Rosenzweig UCLA, Los Angeles, California, USA L. Faillace RadiaBeam, Marina del Rey, California, USA B. Spataro INFN/LNF, Frascati (Roma), Italy A. Valloni CERN, Geneva, Switzerland
	A new S-Band photoinjector is being developed at UCLA that will feature a large accelerating gradient at 160 MeV/m creating a beam with approximately 6.5 MeV at the exit. Because of the large accelerating gradient and other considerations, such as cooling and manufacturing, the new Supergun will be coupled into using a coaxial method, rather than side coupling. With the large accelerating gradient we hope to create very low emittance beams on the order of 0.025 mm mrad. These beams can then be used for a number of purposes, mainly for high quality beams used in FELs. Electric simulations have been done using HFSS and Superfish. Heating and mechanical simulations were done using Ansys. Finally, beam simulations were completed with GPT.

TUIOA03	The MAX IV Linac	linac, gun, storage-ring, injection	400
	S. Thorin, J. Andersson, F. Curbis, M. Eriksson, O. Karlberg, D. Kumbaro, E. Mansten, D.F. Olsson, S. Werin MAX-lab, Lund, Sweden
	The MAX IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF). The linac has also been deigned to handle the high demands of an FEL injector. In the storage ring injection mode, the linac is operated at 10 Hz with a thermionic RF gun and the electron bunches are kicked out from the linac at either 3 GeV or 1.5 GeV to reach the respective storage ring. For the Short Pulse mode the linac will operate at 100 Hz with a high brightness photo cathode gun. Compression is done in two double achromats with positive R56 and the natural second order momentum compaction, T566, from the achromats is used together with weak sextupoles to linearise longitudinal phase space, leaving no need for a linearising harmonic cavity. The achromat design for bunch compression produces very short, high peak power electron pulses, while minimizing emittance increase. In this paper we present the MAX IV linac design and the status of commissioning which started in March 2014.
	Slides TUIOA03 [4.202 MB]

TUIOA04	The New LCLS-II Project : Status and Challenges	linac, cryomodule, undulator, operation	404
	J.N. Galayda SLAC, Menlo Park, California, USA
	The LCLS-II was an upgrade of the LCLS which essentially replicated the LCLS in another tunnel using the middle 1/3 of the SLAC S-band linac. In August 2013, the project was doubled in scope and redirected towards providing MHz-rate X-ray pulses from 0.2 to 5.0 keV while still supporting the ongoing program at the LCLS. The accelerator is now based on a 4.0 GeV SCRF linac installed in the front of the SLAC linac tunnel. Status and challenges of LCLS-II in context of July 2013 recommendation of DOE BESAC for a fully coherent, cw, FEL with photon energies up to ~5 keV.
	Slides TUIOA04 [6.386 MB]

TUIOA05	High-Power Industrial Accelerator ILU-14 for E-Beam and X-Ray Processing	cathode, gun, controls, injection	409
	V.V. Bezuglov, A.A. Bryazgin, K.N. Chernov, B.L. Faktorovich, V.A. Gorbunov, E.N. Kokin, M.V. Korobeynikov, A.N. Lukin, I. Makarov, S.A. Maximov, A.D. Panfilov, V.M. Radchenko, E.A. Shtarklev, A.V. Sidorov, V.V. Tarnetsky, M.A. Tiunov, V.O. Tkachenko, A. YU. Vlasov, L.A. Voronin BINP SB RAS, Novosibirsk, Russia
	Growing interest to product irradiation by E-beams and X-rays calls for dedicated industrial electron accelerators. BINP has developed ILU-14 radio-frequency pulsed linear accelerator capable of providing 100 kW beam at 7.5-10 MeV. The accelerator has fast removable X-ray converter and can operate both in e-beam and X-ray processing modes. The machine utilizes a low frequency (176 MHz) 6-cells SW accelerating structure. BINP developed this machine as a turn-a-key equipment. Technical details and test results will be presented.
	Slides TUIOA05 [4.672 MB]

TUPP006	Design of Relativistic Magnetron for High Power Microwave Generation	simulation, extraction, cathode, cavity	452
	R. Chandra, S.R. Ghodke, A.S. Patel, A. Sharma, S.K. Singh BARC, Mumbai, India
	A Linear Induction Accelerator based upon magnetic storage, utilising magnetic switches has been made and it is capable of providing a 400 kV diode voltage, 4 kA beam current for 100 ns pulse duration with 100 Hz repetition rate. It operates in a very high repetition rate due to the use of magnetic switches in it. The lesser shot to shot variation make this system ideal for a Relativistic Magnetron operation, where a huge dependence of output power on applied voltage and applied current is observed. A relativistic magnetron with axial extraction is analytically designed and simulated for this system. This relativistic magnetron is expected to give a power of 100 MW per pulse when operated in its full rating. The design features of this relativistic magnetron are presented here. This magnetron was designed for an output microwave frequency of 2.52 GHz. *J. Benford, ''Space Applications of High-Power Microwaves'', IEEE Trans. Plasma Sci., vol. 36, no. 3, pp. 569–581, Jun. 2008

TUPP007	Multi Gigawatt High Current Pulsed Electron Accelerator Technology Development Program at BARC	linac, impedance, high-voltage, induction	456
	A. Sharma, R. Agarwal, M. Beg, R. Chandra, H. Choudhary, L.M. Gantayet, S.R. Ghodke, TS. Kolge, R. Kumar, S. Mitra, K.C. Mittal, A.S. Patel, A. Roy, P.C. Saroj, K. Senthil, V.K. Sharma, S.K. Singh BARC, Mumbai, India
	High current intense electron beams were investigated earlier for Flash X-rays and nuclear electromagnetic pulse generation. Starting with moderate parameters of 200 kV, 6 kA, 60 ns pulsed electron beam source from a system named Kilo Ampere Linear Injector (KALI-75) our latest development is KALI-30 GW system rated for 1 MV, 30 kA, 80 ns. First repetitive pulse LINAC without spark gap switching was developed as Linear Induction Accelerator (LIA-200) for technology demonstrations at 100 Hz. Also a repetitive Marx generator coupled reflex triode system to operate at 10 Hz. Next to this series of development LIA-400 has been developed to a capacity of 400 kV, 4 kA, 100 ns, 300 Hz. To make these pulse power systems applicable for big LINAC projects like nToF studies or ADS program, a high current electron gun has also been developed to give 100 A, 2 ns,10 Hz pulses. References [1].Amitava Roy et al, Journal of App. Physics 103, 2008. [2].D. D. P. Kumar, et al. Rev. Sci. Inst., vol. 78, no. 11, 2007. [3].Archana Sharma, et al., IEEE-PS Vol. 39, No. 5, 2011.

TUPP015	Status on Airix Restart	target, induction, timing, operation	462
	A. Georges, J. Beaubernard, V. Bernigaud, L. Buche, Y. Collet, S. Combacon, B. Gouin, G. Grandpierre, J.K. Kranzmann, L. Magnin, R. Nicolas, D. Pierre, F. Poulet, Y. Tailleur, J-L. Verstraete, J. Magnan CEA, Pontfaverger-Moronvilliers, France
	The Airix accelerator has been moved from Moronvilliers to Valduc to be part of the EPURE facility. Airix has been refurbished and restarted. This paper presents the first results and quantification of performances at its new location. M.Mouillet et al., “First results of AIRIX induction accelerator”,XXth LINAC cf.,p.491(2000) *H.Dzitko et al., "operationnal efficiency of Airix accelerator since its commissioning",IPAC2012,p.4017

TUPP020	Beam Dynamics Simulation for FLASH2 HGHG Option	simulation, FEL, undulator, radiation	471
	G. Feng, S. Ackermann, J. Bödewadt, W. Decking, M. Dohlus, Y.A. Kot, T. Limberg, M. Scholz, I. Zagorodnov DESY, Hamburg, Germany K.E. Hacker DELTA, Dortmund, Germany T. Plath Uni HH, Hamburg, Germany
	The free electron laser (FEL) facility at DESY in Hamburg (FLASH) is the world's first FEL user facility which can produce extreme ultraviolet (XUV) and soft X-ray photons. In order to increase the beam time delivered to users, a major upgrade named FLASH II is in progress. The electron beamline of FLASH2 consists of diagnostic and matching sections and a SASE undulator section. A seeding undulator section will be installed in the future. FLASH2 will be used as a seeded FEL as well as a SASE FEL. In this paper, some results of beam dynamics simulation for the SASE option are given at first which includes the parameters selection for the bunch compressors, RF parameters calculation for the accelerating modules and the beam dynamics simulation taking into account the collective effects. Beam dynamics simulation for a single stage HGHG option is based on the work for the SASE option. Electron bunches with low uncorrelated energy spread and small energy chirp are obtained after parameters optimization. The FEL simulation results show that 33.6 nm wavelength FEL radiation with high monochromaticity can be seeded at FLASH2 with a 235 nm seeding laser.

TUPP022	RF Tuning of a S-band Hybrid Buncher for Injector Upgrade of LINAC II at DESY	linac, simulation, target, experiment	478
	Y.C. Nie, M. Hüning, C. Liebig, M. Schmitz DESY, Hamburg, Germany
	LINACII at DESY currently provides 450 MeV electrons for the synchrotron radiation source PETRAIII. The injector upgrade of it aims to improve its reliability and mitigate the radiological activation due to electron losses at hundreds of MeV. Therefore, a 2.998 GHz hybrid buncher has been developed and will be installed in between a pre-buncher and LINAC II. It comprises a 1-cell standing-wave (SW) section for rapid acceleration and a 13-cells travelling-wave (TW) section for further bunching and acceleration. This paper focuses on its rf tuning procedure. The tuning strategy combines a non-resonant bead-pull measurement of complex electric field and a linear model for local reflection coefficient calculation. The tuning result is satisfying. Field unflatness of the TW section has been improved from ±9% to ±4%, and field in the SW section has been enhanced significantly. By using ASTRA simulation, it has been verified that the residual detuning of the structure is acceptable in view of beam dynamics performance.

TUPP030	Design of a High Average Current Electron Source for the CLIC Drive Beam Injector	gun, cathode, emittance, simulation	493
	S. Döbert, N. Chritin CERN, Geneva, Switzerland B. Cadilhon, B. Cassany, J. Gardelle, K. Pepitone CEA, LE BARP cedex, France
	The drive beam injector for CLIC needs to deliver a 4.2 A electron beam for a duration of 140 μs with a repetition rate of 50 Hz. The shot to shot and flat top current stability has to be better than 0.1% to guarantee the beam stability required for CLIC. Based on the experience with the CTF3 injector a thermionic high voltage gun with a gridded cathode has been designed together with a sub-harmonic bunching system to achieve these requirements. The grid will allow controlling the current and eventually feedback on the flattop shape. The gun will operate at 140 kV and an emittance of 14 mm mrad can be obtained. The paper describes the design approach and the results of the systematic electromagnetic simulations to optimize the gun. Care was taken during the mechanical design of the gun to obtain a modular design allowing adjusting for different beam currents and cathode sizes.

TUPP034	Commissioning of the CERN LINAC4 Wire Scanner, Wire Grid and Slit-Grid Monitors at 3 and 12 MeV	linac, emittance, space-charge, diagnostics	502
	F. Roncarolo, U. Raich, F. Zocca CERN, Geneva, Switzerland
	The CERN LINAC4 has been commissioned up to 12 MeV. The H⁻ beam transverse profile distributions were measured by both wire grids and wire scanners. A slit-grid system located on a temporary diagnostics bench was used to characterize the transverse emittance during the two different stages of commissioning: at the exit of the RFQ (3 MeV) and DTL1 (12 MeV). The wire signal is a balance between the negative charge deposited by the stripped electrons from the H⁻ and the charge lost due to secondary emission. Optimal settings were found for the repelling plates used to suppress secondary emission, which were confirmed by electromagnetic simulations. In addition, suppression of the secondary emission due to the beam space charge was observed. The benefit of changing the wire scanner geometry in order to minimize the cross-talk between horizontal and vertical wires and the observation of thermionic emission on carbon wires are also discussed.

TUPP035	Transverse Profile and Emittance Measurements With a Laser Stripping System During the CERN LINAC4 Commissioning at 3 and 12 MeV	laser, emittance, linac, detector	506
	F. Roncarolo, E. Bravin, T. Hofmann, U. Raich, F. Zocca CERN, Geneva, Switzerland G.E. Boorman, A. Bosco, S.M. Gibson, K.O. Kruchinin Royal Holloway, University of London, Surrey, United Kingdom C. Gabor STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom J.K. Pozimski Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	The CERN LINAC4 beam commissioning at 3 and 12 MeV was completed in 2014. A novel system for measuring the transverse beam profile and emittance, based on low power laser stripping and H⁰ detection using a diamond detector, was successfully tested at these two energies. The measurement results agree with the operational slit-grid method within a few percent in terms of both transverse profile and emittance. After describing the general system setup, this remarkable achievement is discussed in detail together with the present limitations, which will be addressed in order to design a laser based emittance monitor for the LINAC4 top energy of 160 MeV.

TUPP066	Commissioning Results of the 2nd 3.5 Cell SRF Gun for ELBE	gun, SRF, cavity, solenoid	578
	A. Arnold, M. Freitag, P. Murcek, J. Teichert, H. Vennekate, R. Xiang HZDR, Dresden, Germany G. Ciovati, P. Kneisel, L. Turlington JLab, Newport News, Virginia, USA
	As in 2007 the first 3.5 cell superconducting radio frequency (SRF) gun was taken into operation at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), it turned out that the specified performance to realize an electron energy gain of 9.4 MeV (Epk=50 MV/m @ Q0=10¹⁰) has not been achieved. Instead, the resonator of the gun was limited by field emission to about one third of these values and the measured beam parameters remained significantly behind the expectations. However, to demonstrate the full potential of this new electron source for the ELBE LINAC, a second and slightly modified SRF gun was developed and built in collaboration with Thomas Jefferson National Accelerator Facility (TJNAF). We will report on commissioning and first results of this new SRF gun. This includes in particular the characterization of the most important RF properties of the cavity as well as their comparison with previous vertical test results.
	Poster TUPP066 [1.220 MB]

TUPP078	High Gain FEL with a Micro-bunch Structured Beam by the Transverse-Longitudinal Phase Space Rotation	FEL, cavity, radiation, cathode	607
	M. Kuriki, Y. Seimiya HU/AdSM, Higashi-Hiroshima, Japan H. Hayano, K. Ohmi KEK, Ibaraki, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan R. Kato ISIR, Osaka, Japan
	FEL is one of the ideal radiation source over the wide range of wavelength region with a high brightness and a high coherence. Many methods to improve FEL gain has been proposed by introducing an active modulation on the bunch charge distribution. The transverse-longitudinal phase-space rotation is one of the promising method to realize the density modulation as the micro-bunch structure. Initially, a beam density modulation in the transverse direction made by a mechanical slit, is properly transformed into the density modulation in the longitudinal direction by the phase-space rotation. That results the longitudinal micro-bunch structure. The micro-bunch structure made with this method has a large tunability by changing the slit geometry, the beam line design, and the beam dynamics tuning. A compact FEL facility based on this method is proposed.
	Poster TUPP078 [0.594 MB]

TUPP086	RAON Superconducting Radio Frequency Test Facility Construction	cavity, radiation, cryogenics, SRF	625
	H. Kim, D. Jeon, Y.W. Jo, Y. Jung, S.A. Kim, W.K. Kim, S.J. Lee, S.W. Nam, G.-T. Park, J.H. Shin IBS, Daejeon, Republic of Korea
	Superconducting Radio Frequency (SRF) test facility for RAON is under construction process. It consists of cryogenic system, clean room for cavity process and assembles vertical test, horizontal test, and the radiation shield. The cryoplant has 330 W (4.5 K equivalent) which supplies 4.5K supercritical helium to the cavity test and cryomodule test bench. Clean rooms are for cavity process and assemble whose class is from 10 to 10000. The layout for the vertical and horizontal test bench is shown and the radiation shield for the test bench is shown to reduce X-ray coming from cavity. To estimate the thickness of concrete, radiation simulation is performed.

TUPP088	The Fabrication of the β=0.12 HWR at RISP	niobium, cavity, target, vacuum	628
	G.-T. Park, H.J. Cha, Y. Jung, H. Kim, W.K. Kim IBS, Daejeon, Republic of Korea
	At RISP, the superconducting cavities have been developed to construct RAON, the heavy ion accelerator. Among the cavities, the fabrication of the QWR (Quarter wave resonator) and the HWR (Half wave resonator)are complete. The detailed fabrication processes including material inspection, forming, the electron beam welding, and the clamp up test are described.

TUPP091	3 BPM Study at PAL ITF	controls, pick-up, laser, interface	637
	M. Žnidarčič I-Tech, Solkan, Slovenia C. Kim, S.J. Lee PAL, Pohang, Kyungbuk, Republic of Korea
	Pohang Accelerator Laboratory (PAL) is building the 4th generation X-ray free electron laser (XFEL) machine. To examine the efficiency of various diagnostic devices an injector test facility (ITF) was constructed. The last part of the ITF is dedicated for evaluation of beam position measurement devices. A “3-BPM-study” was done with 3 Libera Single Pass E BPM modules that were connected to the 3 equidistantly positioned stripline sensors. The aim of the test was to measure the performances of the Libera Single Pass E devices with beam conditions similar to the real pal XFEL machine.

TUPP096	LUE-200 Linac. Status & Development	klystron, neutron, linac, beam-loading	653
	A.P. Sumbaev, A.S. Kayukov, V. Kobets, V. Minashkin, V.G. Pyataev, V.A. Shvets JINR, Dubna, Moscow Region, Russia V. Shabratov JINR/VBLHEP, Moscow, Russia V.N. Shvetsov JINR/FLNP, Moscow Region, Russia
	The general scheme and current status of an electron linear accelerator with an S-band travelling wave (f = 2856 MHz) accelerating structure – a driver for a pulsed neutron source (IREN) at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research - are presented. The parameters of the accelerating system and the measured parameters of the electron beam – pulse-beam current, duration of the current pulse, repetition rate, electron-energy spectrum, and loading characteristics of the accelerating structure - are given. The beginning of the implementation of the project of the second stage of the IREN facility, which forms the basis for the development of the accelerator aimed at increasing its beam power, is reported. Technical solutions underlying the modernization of the accelerator’s electrophysical systems are discussed: accelerating system, RF power supplies,and modulators.

TUPP110	Quasi Nonlinear Plasma Wakefield Acceleration Experiments	plasma, focusing, experiment, emittance	680
	S.K. Barber, G. Andonian, B.D. O'Shea, J.B. Rosenzweig, Y. Sakai, O. Williams UCLA, Los Angeles, USA M. Ferrario INFN/LNF, Frascati (Roma), Italy P. Muggli MPI, Muenchen, Germany
	It is generally agreed that the best way forward for beam driven plasma wakefield acceleration (PWFA) is in the nonlinear or blowout regime. In this regime the expulsion of the plasma electrons from the beam occupied region produces a linear transverse focusing effect and position independent longitudinal accelerating fields, which can, in principle, produce high quality beams accelerated over many meters. However, certain aspects of a linear plasma response can be advantageous, such as the possibility for resonant excitation of wakefields through the use of pulse trains. Exploiting advantages of both linear and nonlinear PWFA may be achievable through the use of low emittance and tightly focused beams with relatively small charge. In this case the beam density can be greater than that of the ambient plasma while simultaneously having a smaller total charge than the plasma electrons contained in a cubic plasma skin depth allowing for blowout in the region of the beam while simultaneously maintaining a quasi linear response in the bulk plasma. Recent experiments at BNL have been aimed at probing various salient aspects of this regime and are presented here.

TUPP111	SwissFEL C-band LLRF Prototype System	LLRF, controls, feedback, klystron	683
	A. Hauff, M. Broennimann, I. Brunnenkant, A. Dietrich, Z. Geng, F. Gärtner, M. Jurcevic, R. Kalt, S. Mair, A. Řežaeizadeh, L. Schebacher, T. Schilcher, W. Sturzenegger PSI, Villigen PSI, Switzerland
	SwissFEL is driven by more than 30 RF stations at different frequencies (S-, C-, X-band). To control the RF a new, in-house developed digital Low Level RF (LLRF) system measures up to 24 RF signals per station and performs a pulse-to-pulse feedback at a repetition rate of 100 Hz. The RF signals are down-converted to a common intermediate frequency. The state-of-the-art digital processing units are integrated into the PSI’s EPICS controls environment. Emphasis has been put on modularity of the system to provide a well-defined path for upgrades. Thus the RF front ends are separated from the digital processing units with their FMC standard interfaces for ADCs and DACs. A first prototype of the LLRF system consisting of the digital back end together with a C-band RF front end was installed in the SwissFEL C-band test facility. In this report the performance of the prototype system has been compared with the LLRF system requirements for SwissFEL. The critical parameters are high intra-pulse phase and amplitude resolutions, good channel-to-channel isolations, very low phase to amplitude modulation and a negligible temperature drift.

TUPP120	Commissioning of BINP Injection Complex VEPP-5	injection, dumping, positron, closed-orbit	702
	A.A. Starostenko, A.E. Levichev, D.A. Nikiforov BINP SB RAS, Novosibirsk, Russia
	New BINP injector complex VEPP-5 consist of S-band linear accelerators (270 and 420MeV), positron converter (at 270 MeV) and damping ring. The injector complex will provide e⁺/e⁻ particles for the 2 colliders at BINP - VEPP-4M and VEPP-2000. After a long construction period the injector is in its commissioning stage now. Positron rate production of 6·10⁸ positrons/pulse and conversion yield of 0.14/GeV and stored positron beam current of 70mA were already achieved.

TUPP121	Limitations for Acceleration of Intermediate Mass Particles with Traveling Wave Structure	operation, acceleration, accelerating-gradient, linac	705
	V.V. Paramonov RAS/INR, Moscow, Russia
	The Disk Loaded Waveguide (DLW) is the mostly used high frequency structure for acceleration of lightweight particles – electrons in the high energy range. DLW parameters are considered for the lower frequency range and lower particle velocity. Physical and technical restrictions for DLW application for the low particles velocity are analyzed. Basing on particularities of acceleration with traveling wave, deep optimization of DLW cells dimensions, the choice of optimal operating phase advance for each DLW section and combination of forward and backward wave modes, it looks possible to create the simple, cost effective acceleration system for intermediate particles acceleration in the moderate velocity range, in some parameters overcoming accelerating system with RF cavities in the standing wave mode.

TUPP123	Design of Novel RF Sources to Reduce the Beam Pace-Charge Effects	cavity, klystron, space-charge, cathode	712
	M. Dal Forno, A. Jensen, R.D. Ruth, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: DOE Traditional RF sources, such as Klystrons, TWT require a magnet (such as a solenoid) in order to maintain the electron beam focusing, compensating the particle repulsion caused by space charge effects. We designed a novel RF source with an alternative approach that reduces beam space charge problems. This paper shows the design of the device, with a new formulation of the Child’s Law, and the mode-beam stability analysis. The electron beam interaction with the cavity fields has been analyzed by means of particle tracking software in order to evaluate the beam bunching and the beam dynamics.
	Poster TUPP123 [0.172 MB]

TUPP128	ECHO-enabled Tunable Terahertz Radiation Generation with a Laser-modulated Relativistic Electron Beam	laser, radiation, FEL, simulation	719
	D. Huang, Q. Gu, Z. Wang, Z.T. Zhao SINAP, Shanghai, People's Republic of China D. Xiang Shanghai Jiao Tong University, Shanghai, People's Republic of China
	A new scheme to generate narrow-band tunable Terahertz (THz) radiation using a variant of the echo-enabled harmonic generation is analyzed. We show that by using an energy chirped beam, THz density modulation in the beam phase space can be produced with two lasers having the same wavelength. This removes the need for an optical parametric amplifier system to provide a wavelength-tunable laser to vary the central frequency of the THz radiation. The practical feasibility and applications of this scheme is demonstrated numerically with a start-to-end simulation using the beam parameters at Shanghai Deep Ultraviolet Free-Electron Laser facility (SDUV). The central frequency of the density modulation can be continuously tuned by either varying the chirp of the beam or the momentum compactions of the chicanes. The influence of nonlinear RF chirp and longitudinal space charge effect have also been studied in our article. We also briefly discuss how one may retrieve the beam longitudinal phase space through measurement of the THz density modulation. \end{abstract}

TUPP133	Optimization of the RF Cavity of the Medical Purpose Electron Linac by Using Genetic Algorithm	cavity, impedance, linac, acceleration	726
	S. Shin, J.-S. Chai SKKU, Suwon, Republic of Korea
	A compact electron linear accelerator for the medical application has been developing at Sungkyunkwan University. Due to this electron linac is attached on the robot arm or gantry, it should be compact enough to be held by the structure. An X-band technology has been used to meet the requirements for the compact linac. Because the particle accelerator is complex and sensitive machine to design it takes a lot of time to get a good performance accelerator. In this research, a special technique named single-objective genetic algorithm for the optimization process has been applied to achieve a better RF cavity design by changing various geometric parameters.

TUPP135	Beam Dynamics Calculations and Magnet Design for Future Measurements of Transverse Beam Break-Up at the S-DALINAC*	linac, experiment, recirculation, sextupole	729
	F. Hug, M. Arnold, L.E. Jürgensen, T. Kürzeder, N. Pietralla, M. Schilling TU Darmstadt, Darmstadt, Germany
	Funding: *Work supported by the BMBF through 05K13RDA The superconducting electron accelerator S-DALINAC at TU Darmstadt produces c.w. electron beams of up to 90 MeV. The S-DALINAC consists of a SC 14-MeV injector linac, a SC main linac and two recirculation paths. Currently a third recirculation is in its final design phase and will be constructed end 2014 in order to achieve an energy of 130 MeV in future. The main linac houses eight 20-cell SRF cavities operated at 3 GHz and 2 K. Due to the occurance of transverse beam break-up, the highest stable beam current obtained so far amounts to 5 μA only, which is below the design beam current of 20 μA but sufficient for the nuclear physics experiments carried out at Darmstadt since 1991. In this work we will present beam-dynamics calculations and newly designed magnets for planned experiments at the S-DALINAC in order to benchmark different strategies of increasing the threshold current for beam break-up.

TUPP140	Observation of >GV/m Decelerating Fields in Dielectric Lined Waveguides	wakefield, radiation, vacuum, experiment	743
	B.D. O'Shea, G. Andonian, K.L. Fitzmorris, S. Hakimi, J. Harrison, J.B. Rosenzweig, O. Williams UCLA, Los Angeles, California, USA M.J. Hogan, V. Yakimenko SLAC, Menlo Park, California, USA
	Recent experimental measurements of the energy lost to wakefields in a dielectric lined waveguide are presented. These measurements demonstrate average decelerating gradients on the order of >1 GV/m, for two different structures. The measurements were made at the Facility for Advanced aCcelerator Experimental Tests (FACET) at SLAC National Laboratory using sub-millimeter diameter fifteen-centimeter long quartz fibers of annular cross section. The unique extremely short, high charge, ultra relativistic beam at FACET (200 fs, 3 nC, 20 GeV) allows the use of dielectric wakefield structures of unprecedented size and length. In addition to experimental results, we support conclusions with simulation and theoretical work. This measurement builds on a large body of work previously performed using dielectric wakefield structures in an effort to provide high gradient accelerating structures for tomorrows linear colliders.

WEIOA04	Phase Locked Magnetrons for Accelerators	injection, cathode, controls, cavity	751
	A.C. Dexter Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	Magnetrons offer lower capital costs and higher efficiencies than klystrons, however are natural oscillators rather than amplifiers. This paper reviews techniques and issues for applying high efficiency L band magnetrons to long pulse, high intensity proton linacs. Reference is made to a proof of principle experiment whereby the phase of an SRF cavity was accurately controlled when energised by a magnetron.
	Slides WEIOA04 [1.224 MB]

THIOB03	Results From the LCLS X-Band Transverse Deflector With Femtosecond Temporal Resolution	FEL, undulator, photon, diagnostics	819
	Y. Ding, F.-J. Decker, V.A. Dolgashev, J.C. Frisch, Z. Huang, P. Krejcik, H. Loos, A. Lutmann, A. Marinelli, T.J. Maxwell, D.F. Ratner, J.L. Turner, J.W. Wang, M.-H. Wang, J.J. Welch, J. Wu SLAC, Menlo Park, California, USA C. Behrens DESY, Hamburg, Germany
	An X-band RF transverse deflector composed of two 1-m-long X-band deflecting structures has been recently commissioned at the Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory. Located downstream of the FEL undulator, this device provides electron beam longitudinal phase space diagnostics in both time and energy which enables reconstruction of the X-ray FEL power profiles with an unprecedented resolution. This talk reports on the progress of this new LCLS X-band transverse deflector, first usage experience and measured results.
	Slides THIOB03 [3.508 MB]

THIOC02	Allison Scanner Emittance Diagnostic Development at TRIUMF	emittance, ion, gun, TRIUMF	829
	A. Laxdal, F. Ames, R.A. Baartman, W.R. Rawnsley, A. Sen, V.A. Verzilov, G. Waters TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada R.V. Hariwal IUAC, New Delhi, India M. Kownacki SFU, Burnaby, BC, Canada R.F. Paris University of Ottawa, Ottawa, Ontario, Canada
	TRIUMF has developed Allison scanners to measure the transverse emittance of both low intensity hadron beams at 10⁴ pps and high intensity electron beams at 10mA for a dynamic range of more than 10¹² in intensity. The devices give high resolution transverse emittance information in a compact package that fits in a single diagnostic box. The talk will present the design and performance of the operating devices.
	Slides THIOC02 [2.349 MB]

THPP003	Cooling of High Pressure Insulating Gas for 3 MeV DC Accelerator: an Alternate Approach	controls, high-voltage, resonance, interlocks	839
	S.R. Ghodke, S. Acharya, R. Barnwal, K.P. Dixit, L.M. Gantayet, B.S. Israel, D. Jayaprakash, K. Mahender, K.C. Mittal, S. Nayak, R.N. Rajan, D.K. Sharma, V. Sharma, S.K. Suneet, D.P. Suryaprakash BARC, Mumbai, India
	3 MeV Accelerator Project working inside the ‘Electron Beam Centre’ (EBC) building at Kharghar, Navi Mumbai. Generally in DC and Pelletron accelerators Nitrogen/SF6 gas is taken out from accelerator tank and it is cooled by separate heat exchanger and blower unit outside the accelerator tank. In our alternate approach we have designed fan/ blower to work under high pressure inside accelerator tank. Fans are designed to work in high pressure SF6 environment at 7 bar absolute pressure with 42 kg/m3 SF6 gas density. Fan throughs air over radiator type finned tube heat exchanger, installed inside accelerator tank. Fan speeds are controlled through variable frequency drive. Two numbers of such assemblies are fabricated, installed and tested in Nitrogen and SF6 gas environment at different pressure and variable fan speed. Performances are recorded and plotted in graphical form. These cooling systems are shown excellent performance in last five years. Paper will discuss about design of cooling system, cooling calculation of fan, fabrication of fan and heat exchanger, 5 TR chiller unit, variable frequency drive, fan performance etc.
	Poster THPP003 [1.644 MB]

THPP004	Design, Development and Initial Results of Solid State Magnetron Modulator	distributed, klystron, induction, impedance	843
	A.R. Tillu, S. Chandan, K.P. Dixit, K.C. Mittal, H.E. Sarukte BARC, Mumbai, India
	A prototype solid state pulse modulator based on Induction Adder Topology has been designed ans is currently being tested on a S Band Pulsed magnetron rated for 3.2M W Peak RF Power. After successful lab tests the modulator is intended for use in cargo scanning and radiography applications. Currently the topology consists of 4 no.s of single turn primaries driven independently at voltages not more than 1000V. The secondary encircles all the four primaries to generate the desired pulsed voltage across the magnetron. The designed output pulse parameters are 50k V, 120A, 4micro s, at a pulse repetition rate of 250 pps. The paper describes the design and development of the Epoxy Cast Pulse transformer and the Low Inductance Primary Circuit. The rise time measured was < 400ns, and the reverse voltage at the end of the pulse was less than 12kV (at 43k V pulse). The testing was done at low PRF, on two different magnetrons having different operating points to demonstrate fairly good impedance independent operating characteristic of the magnetron modulator. Initial test results on the Resistive load and Magnetron load will also be discussed
	Poster THPP004 [1.575 MB]

THPP005	A New High Current and Single Bunch Injector at ELSA	booster, linac, injection, timing	847
	M. Schedler, P. Hänisch, W. Hillert, D. Proft ELSA, Bonn, Germany J. Zappai Uni Bonn, Bonn, Germany
	At the Electron Stretcher Facility ELSA of Bonn University, an increase of the maximum stored beam current from 20 mA to 200 mA is planned for the stretcher ring. In order to keep the desired duty cycle of the post acceleration mode at about 80 \% a new high current injector operating at 3 GHz has been built. It provides an electron beam with an energy of 20 MeV and a beam current of 800 mA in pulsed operation. A prebuncher, travelling wave buncher system and an energy compressing system are installed in order to enhance the beam acceptance of the linac and to reduce the energy spread in order to achieve an improved injection efficiency into the booster synchrotron. For studying accelerators impedances and beam instabilities the linac is able to produce single bunches with a pulse current of 2 A which will be accumulated in the stretcher ring.

THPP012	A Prototype 1 Mev X-Band Linac for Aviation Cargo Inspection	cavity, linac, simulation, accelerating-gradient	853
	M. Jenkins, P.K. Ambattu, G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom S. Andrews, T.A. Cross, C.R. Weatherup e2v, Chelmsford, Essex, United Kingdom P.A. Corlett, P. Goudket, A.R. Goulden, P.A. McIntosh, K.J. Middleman, Y.M. Saveliev, R.J. Smith, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom S.A. Griffiths, M.D. Hancock, T. Hartnett, C. Hill, J.P. Hindley, B.G. Martlew, N. Templeton STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	Aviation cargo Unit Load Device (ULD) containers are typically much smaller than standard shipping containers, with a volume of around 1m3. Standard 3-6 MeV X-ray screening linacs have too much energy to obtain sufficient contrast when inspecting ULD’s, hence a lower 1 MeV linac is required. In order to obtain a small physical footprint, which can be adapted to mobile platform applications a compact design is required, hence X-band technology is the ideal solution. A prototype 1 MeV linac cavity has been designed by Lancaster University, manufactured by Comeb (Italy) and tested at STFC Daresbury Laboratory using an e2v magnetron, modulator and electron gun. The cavity is a bi-periodic π/2 structure, with beam-pipe aperture coupling to simplify the manufacture at the expense of shunt impedance. The design, manufacture and testing of this linac structure is presented.

THPP028	Design and Beamloading-Simulations of a Pre-Bunching Cavity for the CLIC Drive Beam Injector	cavity, beam-loading, simulation, coupling	895
	M. Dayyani Kelisani, S. Döbert, H. Shaker CERN, Geneva, Switzerland H. Shaker IPM, Tehran, Iran
	The CLIC project is developing a multi-TeV center-of-mass electron-positron collider based on high-gradient, room-temperature accelerating structures and a novel two-beam RF power generation scheme. The RF power for the CLIC accelerating structures is provided by the so-called drive beam which is a low energy, high current electron beam. The drive beam will be generated from a high current (up to 5 A) pulsed (142μs) thermionic electron gun and then followed by a bunching system. The bunching system is composed of three sub-harmonic bunchers operating at a frequency of 499.75 MHz, a pre-buncher and a traveling wave buncher both operating at 999.5MHz. The pre-buncher cavity, which has a great importance on minimization the satellite population, should be designed with special consideration of the high beam loading effect due to the high current beam crossing the cavity. In this work we report on RF design, analytical beam loading calculations and simulations for the CLIC drive beam injector pre-buncher cavity.

THPP031	Plans for an ERL Test Facility at CERN	cavity, cryomodule, SRF, linac	905
	E. Jensen, O.S. Brüning, R. Calaga, K.M. Schirm, R. Torres-Sanchez, A. Valloni CERN, Geneva, Switzerland K. Aulenbacher IKP, Mainz, Germany S.A. Bogacz, A. Hutton JLab, Newport News, Virginia, USA M. Klein The University of Liverpool, Liverpool, United Kingdom
	The baseline electron accelerator for LHeC and one option for FCC-he is an Energy Recovery Linac. To prepare and study the necessary key technologies, CERN has started – in collaboration with JLAB and Mainz University – the conceptual design of an ERL Test Facility (ERL-TF). Staged construction will allow the study under different conditions with up to 3 passes, beam energies of up to about 1 GeV and currents of up to 50 mA. The design and development of superconducting cavity modules, including coupler and HOM damper designs, are also of central importance for other existing and future accelerators and their tests are at the heart of the current ERL-TF goals. The ERL-TF could also provide a unique infrastructure for several applications that go beyond developing and testing the ERL technology at CERN. In addition to experimental studies of beam dynamics, operational and reliability issues in an ERL, it could equally serve for quench tests of superconducting magnets, as physics experimental facility on its own right or as test stand for detector developments. This contribution will describe the goals and the concept of the facility and the status of the R&D.

THPP035	Deceleration Measurements of an Electron Beam in the CLIC Test Facility 3	lattice, quadrupole, acceleration, linear-collider	920
	R.L. Lillestøl, S. Döbert CERN, Geneva, Switzerland E. Adli University of Oslo, Oslo, Norway
	The Test Beam Line at the CLIC Test Facility 3 at CERN is a proof-of-principle of the future CLIC decelerators, which will extract a large amount of beam energy for acceleration of the main CLIC beams. The current beamline consists of a FODO lattice with 13 Power Extraction and Transfer Structures (PETS). We discuss beam deceleration measurements of up to 37 %, taking into account effects from the bunch length and the bunch phase. The 12 GHz phase is reproduced based on measurements in a PETS with an uncombined beam. The spectrometer measurements are also compared to predictions based on the beam current and on the produced rf power in the PETS, as well as particle tracking simulations with the Placet code.

THPP038	The Drift Tube Welding Assembly for the Linac4 Drift Tube Linac at CERN	linac, operation, drift-tube-linac, DTL	929
	I. Sexton, A. Cherif, Y. Cuvet, G. Favre, J.-M. Geisser, S. Ramberger, S. Sgobba, T. Tardy CERN, Geneva, Switzerland F.M. Mirapeix DMP, Mendaro, Spain
	The fabrication of the Linac4 Drift Tube Linac (DTL) required the welding assembly of 10⁸ drift tubes (DT) which has been undertaken at the CERN workshop. The design of the DTL is particular in that it was purposely simplified to avoid any position adjustment mechanism for drift tubes in the tank. In consequence, drift tubes have been designed with tight tolerances and parts have been assembled with an optimised welding procedure. Two re-machining stages have been introduced in order to compensate for welding distortions. This paper discusses the various assembly stages with a view on the final precision that has been achieved.
	Poster THPP038 [8.665 MB]

THPP039	Electron Beam Welding and Vacuum Brazing Characterization for SRF Cavities	vacuum, niobium, cavity, interface	932
	N. Valverde Alonso, S. Atieh, I. Aviles Santillana, S. Calatroni, O. Capatina, L.M.A. Ferreira, F. Pillon, M. Redondas Monteserin, T. Renaglia, K.M. Schirm, T. Tardy, A. Vacca CERN, Geneva, Switzerland
	In the framework of the SPL R&D effort at CERN, development design efforts study the joining of dissimilar metals: bulk niobium for the superconducting RF cavities and stainless steel (316LN) or titanium alloys (Ti-6Al-4V and Nb55Ti) for the cryostats. Joining techniques of electron beam welding (EBW) and vacuum brazing are particularly important for these applications. These processes have been used in the accelerator community and developed into generally accepted “best practice”. Studies were performed to update the existing knowledge, and comprehensively characterise these joints via mechanical and metallurgical investigations using modern available technologies. The developed solutions are described in detail, some currently being applied uniquely at CERN.
	Poster THPP039 [5.324 MB]

THPP055	High Power Density Test of PXIE MEBT Absorber Prototype	simulation, radiation, experiment, focusing	973
	A.V. Shemyakin, C.M. Baffes Fermilab, Batavia, Illinois, USA
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the United States Department of Energy One of the goals of the PXIE program at Fermilab is to demonstrate the capability to form an arbitrary bunch pattern from an initially CW 162.5 MHz H⁻ bunch train coming out of an RFQ. The bunch-by-bunch selection will take place in the 2.1 MeV Medium Energy Beam Transport (MEBT) by directing the undesired bunches onto an absorber that needs to withstand a beam power of up to 21 kW, focused onto a spot with a ~2 mm rms radius. Two prototypes of the absorber were manufactured from molybdenum alloy TZM, and tested with a 28 keV DC electron beam up to the peak surface power density required for PXIE, 17W/mm2. Temperatures and flow parameters were measured and compared to analysis. This paper describes the absorber prototypes and key testing results.

THPP058	A Review of Emittance Exchanger Beamlines: Past Experiments and Future Proposals	cavity, emittance, laser, experiment	982
	J.C.T. Thangaraj Fermilab, Batavia, Illinois, USA
	Emittance exchangers (EEX) are advanced phase space manipulation schemes where the transverse phase space of the electron beam is exchanged with the longitudinal phase space. The first experimentally demonstrated concept of the emittance exchanger at the A0 photoinjector at Fermilab used a transverse deflecting cavity (TDC) sandwiched between two doglegs. In this talk, I will briefly review the history of the emittance exchange beamline experiments from a low charge beam without RF chirp to a high charge beam with RF chirp including collective effects such as coherent synchrotron radiation. I will also describe how shaping application have been spawned based on EEX. I will then review future schemes that has been proposed and propose two additional schemes of EEX that can be implemented in existing modern linacs. As an example, we present an improved emittance exchanger scheme that uses a TDC sandwiched between two chicanes. The significant advantage of this scheme is that it allows the use of the expensive transverse deflecting cavity for diagnostics and still allows the flexibility to use the existing beamline either as a bunch compressor or an emittance exchanger.

THPP059	Z-Shaper: A Picosecond UV Laser Pulse Shaping Channel at the Advanced Superconducting Test Accelerator	laser, experiment, linac, controls	986
	J.C.T. Thangaraj, D.R. Edstrom, A.H. Lumpkin, J. Ruan Fermilab, Batavia, Illinois, USA B. Beaudoin UMD, College Park, Maryland, USA
	Many accelerator applications require a longitudinally shaped electron beam profile for studies ranging from THz generation to dielectric wakefield acceleration. An electron beam profile can be shaped through many techniques in both electron beam generation, such as with a DAZZLER or in ellipsoidal pulse generation, and beam transport, using an emittance exchanger or linearizing harmonic cavity. In this paper, shaping of a UV pulse with length on the order of picoseconds is examined using alpha-BBO crystals in the Advanced Superconducting Test Accelerator (ASTA) drive laser. A relatively economical solution to effect a predictable and tunable longitudinal bunch shape, profiles have been generated and observed using a Hamamatsu C5680 streak camera, and the results are compared with the analytical theory.

THPP075	Development of Superconducting Spoke Cavity for Electron Accelerators	cavity, simulation, multipactoring, acceleration	1030
	T. Kubo, T. Saeki KEK, Ibaraki, Japan E. Cenni, H. Fujisawa, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan R. Hajima, M. Sawamura JAEA, Ibaraki-ken, Japan
	Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. We have launched a development program of a superconducting spoke cavity for electron acceleration, in order to realize a compact industrial-use X-ray source with the laser-Compton scattering. Efforts for optimizing a cavity design by the electromagnetic field simulation, tracking of multipactor electrons and mechanical property calculations have been continued so far. The optimization processes reached the final stage, and studies toward fabrication processes started. In this presentation, we will show results and processes of the optimization. Attempts to fabricate the spoke cavity, which have just begun, will also be presented.

THPP084	Cyclotron-Undulator Cooling of Electron Beams	undulator, cyclotron, FEL, simulation	1041
	S.V. Kuzikov, I.V. Bandurkin, A.V. Savilov IAP/RAS, Nizhny Novgorod, Russia A.V. Savilov NNGU, Nizhny Novgorod, Russia
	XFELs require high-quality electron beams which can be produced in damping rings. For XFEL, based on Compton scattering of laser light, instead of the damping ring we consider a new compact device where electrons move in the undulator with axial DC magnetic field. In this undulator electrons move near resonant condition, rotating with cyclotron frequency and wiggling at similar bounce frequency. Such undulator allows compensation of the initial velocity spread by perturbations of the longitudinal velocities caused by transverse wiggling. Calculation show that ~1% velocity spread of 5 MeV electron beam (typical for photoinjectors) can be reduced to ~0.01% at distance as long as 20 undulator periods. In the advanced scheme, where the described undulators alternate with sections of the cyclotron radiation, energy spread as small as 0.001% is reachable. Calculations show that this principle works also for high energy beams (100 MeV and more), where RF undulator instead of DC-magnet undulator is preferable.
	Poster THPP084 [0.713 MB]

THPP096	RF Coaxial Resonator for Investigating Multipactor Discharges on Metal and Dielectric Surfaces	multipactoring, vacuum, experiment, coupling	1074
	M. El Khaldi, W. Kaabi, P. Lepercq, Y. Peinaud LAL, Orsay, France
	Multipactor discharge is a phenomenon in which electrons impact one or more material surfaces in resonance with an alternating electric field. The discharge can occur for a wide range of frequencies, from the MHz range to tens of GHz, and in wide array of geometries if the impacted surface has a secondary electron emission (SEE) yield larger than one. The discharge can take place on a single surface or between two surfaces. A novel coaxial resonator to investigate two-surface multipactor discharges on metal and dielectric surfaces in the gap region under vacuum conditions has been designed and tested. The resonator is ~ 100 mm in length with an outer diameter of ~ 60 mm (internal dimensions). A pulsed RF source delivers up to 30 W average power over a wide frequency range 650-900 MHz to the RF resonator. The incident and reflected RF signals are monitored by calibrated RF diodes. An electron probe provides temporal measurements of the multipacting electron current with respect to the RF power. These experiments were successful in identifying multipacting and allowed us the evaluation of a home made sputtered titanium nitride (TiN) thin layers as a Multipactor suppressor.

THPP100	Result of MHI 2-Cell Seamless Dumb-Bell Cavity Vertical Test	cavity, superconducting-cavity, linac, vacuum	1087
	K. Okihira, H. Hara, N. Ikeda, F. Inoue, K. Sennyu MHI, Kobe, Japan R.L. Geng, R.A. Rimmer JLab, Newport News, Virginia, USA E. Kako KEK, Ibaraki, Japan
	MHI have supplied several 9-cell cavities for STF (R&D of ILC project at KEK) and have been considering production method for stable quality and cost reduction, seamless dumb-bell cavity was one of them. We had fabricated a 2 cell seamless dumb-bell cavity for cost reduction and measured RF performance in collaboration with JLab, KEK and MHI. Surface treatment recipe for ILC was applied for MHI 2-cell cavity and vertical test was performed at JLab. The cavity reached Eacc=32.4MV/m after BCP and EP. Details of the result are reported.

THPP102	On Nonlinear Dynamics of a Sheet Electron Beam	emittance, plasma, electronics, brightness	1090
	H.Y. Barminova MEPhI, Moscow, Russia
	In collisionless approximation the nonlinear dynamics of a charged particle beam is studied. Nonlinear oscillations of the beam radius appear due to external and self-consistent nonlinear forces. To study such oscillations the model is applied based on the kinetic distribution function dependent on the particle motion integrals. The 4th-order equation for the beam radius is obtained. The numerical solutions of the equation are analyzed. The cases of strong and weak nonlinearities caused by the own beam fields are discussed. In the case of weak deviation of the beam parameters from equilibrium ones the effective emittance growth isn't observed.

THPP103	Low Dose X-Ray Radiation Source for Angiography Based on Channeling Radiation Principle	radiation, synchrotron, optics, synchrotron-radiation	1093
	T.V. Bondarenko, Yu.D. Kliuchevskaia, S.M. Polozov MEPhI, Moscow, Russia
	Angiography is one of the most reliable and contemporary procedure of the vascular system imaging. X-ray spectrums provided by all modern medical angiographs are too broad to acquire high contrast images and provide low radiation dose at the same time. The new method of narrow X-ray spectrum achieving is based on the idea of channelling radiation application. The X-ray filters used in this method allows eliminating the high energy part of the spectrum and providing dramatic dose reduction. The scheme of the facility including the X-ray filter is discussed. The results of the spectrum analysis for the channelling radiation source and typical angiography X-ray tube are discussed. Doses obtained by the water phantom and contrast of the iodine agent image are also provided for both cases.

THPP104	Simulation of the Electron Beam Dynamics in the Biperiodical Structure	simulation, coupling, Windows, impedance	1096
	Yu.D. Kliuchevskaia, T.V. Bondarenko, S.M. Polozov MEPhI, Moscow, Russia
	А biperiodical accelerating structure (BAS) with operating frequency 27 GHz for the 6 MeV compact radiotherapy electron accelerator is considered. The operating frequency 27 GHz allows to significantly reduce the facility sizes, unlike the S-, X- and C-band operating linacs. The optimal geometrical parameters of BAS necessary for π/2 mode were defined by means of accelerating and coupling cell tuning. The BAS coupler was also simulated. Results of the electron beam dynamics analysis in designed structure are also discussed.

THPP112	Multipacting Optimization of a 750 MHz RF Dipole	dipole, cavity, simulation, collider	1111
	A. Castilla, J.R. Delayen ODU, Norfolk, Virginia, USA A. Castilla DCI-UG, León, Mexico A. Castilla, J.R. Delayen JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Crab crossing schemes have been proposed to re-instate luminosity degradation due to crossing angles at the interaction points in next generation colliders to avoid the use of sharp bending magnets and their resulting large synchrotron radiation generation, highly undessirable in the detector region. The rf dipole has been considered for a different set of applications in several machines, both rings and linear colliders. We present in this paper a study of the effects on the multipacting levels and location depending on geometrical variations on the design for a crabbing/deflecting application in a high current (3/0.5 A), high repetition (750 MHz) electron/proton collider, as a matter to provide a comparison point for similar applications of rf dipoles.

THPP114	The SwissFEL RF Gun: Manufacturing and Proof of Precision by Field Profile Measurements	gun, cathode, coupling, vacuum	1117
	U. Ellenberger, H. Blumer, M. Kleeb, L. Paly, M. Probst Paul Scherrer Institute, Villigen PSI, Switzerland M. Bopp, A. Citterio, H. Fitze, J.-Y. Raguin, A. Scherer, L. Stingelin PSI, Villigen PSI, Switzerland
	The high brightness electron source for SwissFEL is an in-house built 2.6 cell normal-conducting RF gun which is scaled to the RF frequency of 2'998.8 MHz. The RF gun is capable of operating at 100 Hz repetition rate and produces electron bunches at the exit of the RF gun of an energy of 7 MeV. Key features of the RF gun are described and how they have been implemented in the manufacturing process. RF field measurements of the RF gun are presented to account for the mechanical precision reached after manufacturing. The RF gun has been thoroughly tested in the SwissFEL injector test facility.

THPP115	PKU 2.45 GHz Microwave Driven H⁻ Ion Source Performance Study	ion, ion-source, operation, experiment	1120
	T. Zhang, J.E. Chen, Z.Y. Guo, S.X. Peng, H.T. Ren, Y. Xu, J.F. Zhang, J. Zhao PKU, Beijing, People's Republic of China A.L. Zhang University of Chinese Academy of Sciences, Beijing, People's Republic of China
	Funding: This work is supported by the National Science Foundation of China (Grant Nos. 11175009, 91126004 and 11305004) 　　In a high intensity volume-produced H⁻ ion source, H⁻ ion production processes are great affected by electron temperature and gas pressure distribution within the discharge chamber. The H-/e ratio within an extracted H⁻ ion beam is much depended on the electron absorption within the extraction system. At Peking University (PKU), lots of experiments were carried out for better understanding H⁻ processes and electron dump on our 2.45 GHz microwave driven Cs-free permanent magnet volume-produced H⁻ source. Detail will be given in this paper. Author to whom correspondence should be addressed. Electronic mail: sxpeng@pku.edu.cn.
	Poster THPP115 [2.252 MB]

THPP120	Status of Radio-Frequency (RF) Deflectors at Radiabeam	cavity, simulation, impedance, laser	1134
	L. Faillace, R.B. Agustsson, J.J. Hartzell, A.Y. Murokh, S. Storms RadiaBeam, Santa Monica, California, USA
	Radiabeam Technologies recently developed an S-Band normal-conducting Radio-Frequency (NCRF) deflecting cavity for the Pohang Accelerator Laboratory (PAL) in order to perform longitudinal characterization of the sub-picosecond ultra-relativistic electron beams. The device is optimized for the 135 MeV electron beam parameters. The 1m-long PAL deflector is designed to operate at 2.856 GHz and features short filling time and femtosecond resolution. At the end of 2012, we delivered an X-band Traveling wave RF Deflector (XTD) to the ATF facility at Brookhaven National Lab. The device is optimized for the 100 MeV electron beam parameters at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory, and is scalable to higher energies. The XTD is designed to operate at 11.424 GHz, and features short filling time, femtosecond resolution, and a small footprint. The XTD is currently being assembled at ATF for high-power operation and conditioning results will be reported soon.

THPP121	Injector System for the IR-FEL at RRCAT	beam-loading, linac, FEL, cavity	1137
	L. Faillace, R.B. Agustsson RadiaBeam, Santa Monica, California, USA A. Kumar, K.K. Pant RRCAT, Indore (M.P.), India
	An infrared (IR) free-electron laser (FEL) has been proposed to be built at the Raja Ramanna Centre for Advanced Technology (RRCAT). RadiaBeam is currently involved in the design of the RRCAT FEL's injector system. The injector will deliver an electron beam with a variable energy (from 15 up to 40 MeV) and 1.5 nC at 36.6 MHz repetition rate. We show here the beam dynamics of the beam transport through the injector as well as the RF design and mechanical model of the system. * S. Krishnagopal et al., PRELIMINARY DESIGN OF THE PROPOSED IR-FEL IN INDIA, RRCAT, Indore, M.P. 452013, India

THPP123	Experience of Operation of the Electron Linear Accelerator Based on Parallel Coupled Accelerating Structure	cavity, controls, gun, multipactoring	1144
	A.E. Levichev, A.M. Barnyakov, D.A. Nikiforov BINP SB RAS, Novosibirsk, Russia Y.D. Chernousov ICKC, Novosibirsk, Russia V. Ivannikov, I.V. Shebolaev ICKC SB RAS, Novosibirsk, Russia
	An electron linear accelerator based on parallel coupled accelerating structure was developed and produced by Budker Institute of Nuclear Physics SB RAS and Institute of Chemical Kinetics and Combustion SB RAS. Short and long versions of the accelerating structure at 2450 MHz were built. For easy disassembly electrical and vacuum connections of the first (short) structure were made using indium seals. The second structure was brazed. Now the accelerator is in operation and used to study the accelerating and RF technologies. In the report the features of the accelerator are presented, including the design and characteristics of RF antenna and solid-state switch for the electron gun. Test results of the long parallel coupled accelerating structure are discussed. Observations made on the short structure surface after it had been opened are depicted. Now the short structure undergoes certain modifications in order to accelerate higher beam currents.

THPP124	Wakefields in the Superconducting RF Cavities of LCLS-II	cavity, linac, wakefield, niobium	1147
	K.L.F. Bane, T.O. Raubenheimer SLAC, Menlo Park, California, USA A. Romanenko, V.P. Yakovlev Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Department of Energy contract DE–AC02–76SF00515. The superconducting cavities in the linacs of LCLS-II are designed to operate at 2K, where cooling costs are very expensive. In addition to an unavoidable static load and the dynamic load of the fundamental 1.3 GHz accelerating rf, there will be higher order mode (HOM) power deposited by the beam. Due to the very short bunch length the LCLS-II beam spectrum extends into the THz range. Ceramic absorbers, cooled to 70K and located between cryomodules, are meant to absorb much of this power; understanding their effectiveness, however, is a challenging task. In this report we calculate the amount of power radiated by the beam in the different portions of the linac as the bunch length is changed by the bunch compressors. We consider both the steady state radiation as well as transients that arise at the beginning of the linac structures. In addition, transitions due to changes in the vacuum chamber aperture at the ends of the linacs are also considered. Finally, under the assumption that all the wake power ends up in the SRF cavity walls, we estimate the wall heating and the possibility of breaking the Cooper pairs and quenching the cavities.

THPP125	Super-Compact SLED System Used in the LCLS Diagnostic System	cavity, coupling, klystron, impedance	1151
	J.W. Wang, S.G. Tantawi, C. Xu SLAC, Menlo Park, California, USA
	Funding: * Work supported by Department of Energy contract DE–AC03–76SF00515. At SLAC, we have designed and installed an X-band radio-frequency transverse deflector system at the LCLS for measurement of the time-resolved lasing effects on the electron beam and extraction of the temporal profile of the pulses in routine operations. We have designed an X-Band SLED system capable design to augment the available klystron power and to double the kick.

THPP126	Design of the High Repetition Rate Photocathode Gun for the CLARA Project	cavity, gun, simulation, multipactoring	1155
	B.L. Militsyn, L.S. Cowie, P. Goudket, J.W. McKenzie, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom T.J. Jones STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom V.V. Paramonov, A.K. Skasyrskaya RAS/INR, Moscow, Russia
	The CLARA injector is required to deliver ultrashort singe electron pulses with a charge of 250 pC following with a repetition rate of 100 and/or 400 Hz. It should also provide 2 us trains of twenty 25 pC pulses with a repetition rate 100 Hz. To meet this challenge, a 1.5 cell S-band photocathode gun with a field of up to 120 MV/m and coaxial coupling has been chosen. The length of the first cell of 0.5 is decided on the basis of beam dynamic simulation with the goal to obtain optimal for CLARA parameters. In order to improve amplitude and phase stability of the RF field, the gun is equipped with RF probes, which will provide feedback to the RF system. The gun and coupler were designed to accept up to 10 MW peak and 10 kW average RF powers. Cooling will be achieved by water channels cut into the bulk of the copper. The coupler will transition from waveguide to coax using an innovative H-shaped dual feed system that cancels out any dipole mode components and allows tuning of the match. The RF and mechanical design of the CLARA high brightness photocathode gun along with beam dynamics simulations are presented in this paper.

THPP129	Carbon Field Emission Strip Cathode Electron Source	cathode, simulation, vacuum, focusing	1
	T.V. Bondarenko, A.I. Botyachkova, G.G. Karpinskiy, S.A. Polikhov, G.B. Sharkov Siemens Research Center, Moscow,, Russia A.I. Botyachkova, G.G. Karpinskiy National Research Nuclear University (MEPhI), Moscow, Russia A.E. Geisler, O. Heid Siemens AG, Erlangen, Germany
	Over the recent years carbon nanostructure cathodes have become promising as a high brightness electron sources with large working area for field emission structures. Measurements and calculations of a field emission strip cathode based on carbon structure and a unit for its investigation are presented in the article. For measuring of the cathode emitting properties and determination of the electrons initial parameters used in the electron beam computer simulation the experimental setup is been developed. The setup consists of the high-voltage triode electrode system and allows to investigate the voltage-current characteristics of the cathode and to estimate the electron distribution of the beam on the anode surface. The anode electron distribution evaluations are processed by the measurements of the emitted X-ray focal spot on the anode by application of the CCD camera. Verification of the simulated electron beam dynamics can be obtained by application of the experimentally acquired data.
	Poster THPP129 [4.088 MB]

THPP133	LLRF System for the CEBAF Separator Upgrade	cavity, controls, extraction, LLRF	1171
	T. E. Plawski, R. Bachimanchi, C. Hovater, D.J. Seidman, M.J. Wissmann JLab, Newport News, Virginia, USA
	The Continuous Electron Beam Accelerator Facility (CEBAF) energy upgrade from 6 GeV to 12 GeV includes the installation of four new 750 MHz deflecting, normal conducting cavities in the 5th pass extraction region. This system will work together with existing 499 MHz RF Separator in order to allow simultaneous delivery of the beam to four CEBAF experimental halls. The RF system employs two digital LLRF systems controlling four cavities in a vector sum. Cavity tune information of the individual cavities is also obtained using a multiplexing scheme of the forward and reflected RF signals. In this paper we will present detailed LLRF design and current status of the CEBAF 750 MHz beam extraction system.

THPP136	Study of Femtosecond Electron Bunch Generation at t-ACTS, Tohoku University	gun, injection, bunching, radiation	1178
	S. Kashiwagi, H. Hama, F. Hinode, A. Lueangaramwong, T. Muto, I. Nagasawa, S. Nagasawa, K. Nanbu, Y. Shibasaki, K. Takahashi, C. Tokoku Tohoku University, Research Center for Electron Photon Science, Sendai, Japan N.Y. Huang NSRRC, Hsinchu, Taiwan
	We are conducting a beam experiment of sub-picosecond electron bunch generation at a test accelerator as a coherent terahertz source (t-ACTS), Tohoku University. In the t-ACTS, the intense coherent terahertz radiation will be generated from an undulator and an isochronous accumulator ring based on the sub-picoseconds bunches. The accelerator is composed of a thermionic cathode rf gun, alpha magnet and 3 m-long accelerating structure. A velocity bunching scheme in accelerating structure is applied to generate the short electron bunch. The thermionic rf gun consists two independent cavities has been developed, which is capable of manipulating the beam longitudinal phase space. To produced femtosecond electron bunch, the longitudinal phase space distribution of the beam entering the accelerating structure is optimized by changing the rf gun parameters. The bunch length is measured by observing an optical tradition radiation with a streak camera. In the study of femtosecond electron bunch generation, a relation between the rf gun parameters and the bunch length after compression was investigated. The preliminary results of experiments will be described in this conference.

THPP139	800MeV Linear Accelerator Development for HLS Upgrade	linac, klystron, operation, injection	1189
	K. Jin, Y. Hong, G. Huang, D. Jia, S.C. Zhang USTC/NSRL, Hefei, Anhui, People's Republic of China
	Hefei Light Source (HLS) was mainly composed of an 800 MeV electron storage ring and a 200 MeV constant-impedance Linac functioning as its injector in NSRL PhaseⅠ. A new Linac has been developed successfully in view of the Full Energy Injection and the Top-up Injection scheme will be adopted in the HLS upgrade. In this paper, an 800MeV linear accelerating system construction, the constant-gradient structure with the symmetry couplers will be described in detail. The microwave system, the manufacture technology, the RF measurement, the high power testing and the accelerating system operation with beam currents are presented.

THPP140	High Transparent Matched Window for Standing Wave Linear Accelerators	linac, vacuum, network, coupling	1192
	A. Leggieri, F. Di Paolo, D. Passi Università degli Studi di Roma "Tor Vergata", Roma, Italy A. Ciccotelli, G. Felici S.I.T., Aprilia, Italy
	This paper proposes a particular Dielectric Window (DW) for Standing Wave (SW) Linear Accelerators (LINAC’s). This study investigates the in-frequency return loss behavior of the LINAC, in order to improve matching and transmitting conditions while maintaining the optimum coupling between LINAC and High Power Microwave (HPMW) source. Device design is single-frequency based and considers the DW interface as an Input Matching Network (IMN) at the LINAC Normal Mode (NM) working frequency. Thus, design formulas are provided and Computer Aided Design (CAD) techniques are proposed. A prototype has been made and tested by performing cold S-parameter and Percentage Depth Dose (PDD) measurements of a LINAC with the proposed DW and with a traditional DW. The proposed device offers more energy transport attitude over the traditional DW, as shown by a return loss increase of 167% and an output electron energy increase of 5.5% while maintaining the same LINAC input power settings. This solution can offer a decrease of power line size, weight and cost. An after brazing global improvement of the accelerator figures of merit is also possible, as this study have demonstrated. [1]Hiroyuki Arai, 1986 [2]K. Hirano, 1995 [3]Y. Otake, 1995 [5]A. Leggieri, 2014 [6]A. C. Ugural, 2003 [7]A. Leggieri, 2014 [8]F. Di Paolo, 2000 [9]N. Marcuvitz, 1951

FRIOA06	AWAKE: Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN	plasma, proton, laser, experiment	1196
	E. Gschwendtner CERN, Geneva, Switzerland
	Plasma wakefield acceleration is a promising alternative reaching accelerating fields a magnitude of up to 3 higher (GV/m) when compared to conventional RF acceleration. AWAKE, world’s first proton-driven plasma wakefield experiment, was launched at CERN to verify this concept. In this experiment proton bunches at 400 GeV/c will be extracted from the CERN SPS and sent to the plasma cell, where the proton beam drives the plasma wakefields and creates a large accelerating field. This large gradient of ~GV/m can be achieved by relying on the self-modulation instability (SMI) of the proton beam; when seeded by ionization through a short laser pulse, a train of micro-bunches with a period on the order of the plasma wavelength (~mm) develops, which can drive such a large amplitude wake from a long proton bunch (~12 cm). An electron beam will be injected into the plasma to probe the accelerating wakefield. The AWAKE experiment is being installed at CERN in the former CNGS facility, which must be modified to match the AWAKE requirements. First proton beam to the plasma cell is expected by end 2016.
	Slides FRIOA06 [7.276 MB]

Paper

Title

Other Keywords

Page

MOIOB02

Optimizing RF Linacs as Drivers for Inverse Compton Sources: the ELI-NP Case

emittance, linac, laser, photon

16

C. Vaccarezza, D. Alesini, M. Bellaveglia, R. Boni, E. Chiadroni, G. Di Pirro, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, B. Spataro, P. Tomassini
INFN/LNF, Frascati (Roma), Italy
A. Bacci, D.T. Palmer, V. Petrillo, A.R. Rossi, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
I.V. Drebot
Universita' degli Studi di Milano e INFN, Milano, Italy
A. Giribono, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy

The design guide-lines of RF Linacs to fulfill the requirements of high spectral density Inverse Compton Sources for the photo-nuclear science are mostly mutuated from the expertise coming from high brightness electron Linacs driving X-ray FEL's. The main difference is the quest for maximum phase space density (instead of peak brightness), but many common issues and techniques are exploited, in order to achieve an optimum design and lay-out for the machine. A relevant example in this field is the design of the hybrid C-band multi-bunch RF Linacs for the ELI-NP Gamma Beam System, aiming at improving by two orders of magnitude the present state of the art in spectral density available for the gamma-ray beam produced.

Slides MOIOB02 [2.542 MB]

MOIOB03

Generation and Acceleration of Low-Emittance, High-Current Electron Beams for SuperKEKB

emittance, gun, laser, wakefield

21

M. Yoshida, N. Iida, S. Kazama, T. Natsui, Y. Ogawa, S. Ohsawa, L. Zang, X. Zhou
KEK, Ibaraki, Japan

KEK e⁻/e⁺ linac is now in a final stage of upgrade for SuperKEKB. One of the key issues is to stably generate and accelerate a low-emittance, high charge electron beam for SuperKEKB (a couple of single-bunched beams with a charge of 5 nC and a normalized emittance of 20 mm-mmrad each).

Slides MOIOB03 [3.981 MB]

MOIOB04

Current Status of PAL-XFEL

undulator, gun, linac, experiment

26

I.S. Ko, J.H. Han
PAL, Pohang, Kyungbuk, Republic of Korea

The PAL-XFEL project aims to produce 0.1~nm coherent X-ray laser to photon beam users. In order to produce such photons, there are 10 GeV electron linac based on S-band normal conducting accelerating structures and a 150 m long out-vacuum undulator system. The project was already started in April 2011, and the 1.1 km long building is expected to be completed by December 2014. The injector test facility (ITF) which is for a test of the first 139 MeV section of the main linac has been installed and is in normal operation at the extension of the PLS linac building. In this paper, we introduce the project in general, a brief summary of site preparation and building construction, beam test results of ITF, and test results of subsystems produced by domestic manufacturers

Slides MOIOB04 [9.901 MB]

MOIOC01

Status of Superconducting Electron Linac Driver for Rare Ion Beam Production at TRIUMF

cavity, cryomodule, linac, TRIUMF

31

R.E. Laxdal, F. Ames, R.A. Baartman, I.V. Bylinskii, Y.-C. Chao, D. Dale, K. Fong, E.R. Guetre, P. Kolb, S.R. Koscielniak, A. Koveshnikov, M.P. Laverty, Y. Ma, M. Marchetto, L. Merminga, A.K. Mitra, N. Muller, R.R. Nagimov, T. Planche, W.R. Rawnsley, V.A. Verzilov, Z.Y. Yao, Q. Zheng, V. Zvyagintsev
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

A MW class cw superconducting electron linac is being installed at TRIUMF as a driver for radioactive beam production through photo-fission. The ARIEL e-linac will house five 1.3GHz nine-cell cavities in three cryomodules and accelerate up to 10mA of electrons to 50MeV. A first phase of installation will see three cavities in two cryomodules installed by the end of 2014. Presently the injector cryomodule is installed and undergoing cryogenic and rf characterizations and beam acceleration tests with beam from the 300kV DC gun. The second cryomodule is being prepared for first tests. The linac status including descriptions and operating performance of installed cryogenic and rf systems, electron gun performance, cryomodule performance and the results of first beam acceleration tests will be reported.

Slides MOIOC01 [6.383 MB]

MOPP002

Design of a Superconducting Quarter-Wave Resonator for eRHIC

cavity, linac, SRF, niobium

49

S.V. Kutsaev, Z.A. Conway, M.P. Kelly, B. Mustapha, P.N. Ostroumov
ANL, Argonne, USA
S.A. Belomestnykh, I. Ben-Zvi
Stony Brook University, Stony Brook, USA
S.A. Belomestnykh, I. Ben-Zvi, Q. Wu, W. Xu
BNL, Upton, Long Island, New York, USA
B. P. Xiao
SBU, Stony Brook, New York, USA

Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 and by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357
The electron-ion collider project (eRHIC) at Brookhaven National Laboratory requires a 50 mA 12 MeV electron injector linac for eRHIC main linac and an SRF electron gun for a Coherent electron Cooling (CeC) linac. The necessity to deal with long electron bunches required for both the eRHIC injector and the coherent electron cooler sets the frequency requirement of 84.5 MHz. Quarter wave resonator is a perfect choice for this frequency because of its dimensions, RF parameters and good experience with manufacturing and using them at ANL. Here we present the design and optimization of an 84.5 MHz 2.5 MV superconducting quarter-wave cavity suitable for both machines. One such QWR will be used as a bunching cavity in the injector linac, the other one as the photoemission electron source for the CeC linac. In addition to the optimization of the QWR electromagnetic design we will discuss the tuner design, approaches to cavity fabrication and processing.

MOPP004

Design and Development of Pulsed Modulators for RF Electron Linacs

linac, klystron, gun, operation

55

K.P. Dixit, S. Chandan, N. Chaudhary, R.B. Chavan, L.M. Gantayet, S.R. Ghodke, M. Kumar, K.C. Mittal, H.E. Sarukte, A.R. Tillu, H. Tyagi, V. Yadav
BARC, Mumbai, India

Pulsed Modulators required for RF sources, based on klystrons and magnetrons, for RF electron linacs have been designed and developed at Electron Beam Centre, BARC, Mumbai, India. Electron guns in these linacs have also been powered by pulsed modulators. Line-type modulators, as well as IGBT-based solid-state modulators have been developed for these applications. A 150 kV/100 A line-type modulator has been tested on klystron to generate 7 MW peak RF Power. Magnetron modulator has undergone testing up to 40 kV, 165 A on resistive load. Solid-state modulator, using fractional-turn pulse transformer has been designed, developed and tested successfully on magnetron load up to output power of 1.3 MW peak. A transformerless solid-state modulator for electron gun of 6 MeV cargo-scanning linac, uses the Marx adder configuration and has been successfully tested up to 40 kV. In addition, line-type modulators for electron guns up to 85 kV have been successfully commissioned and are in operation in the linac systems. This paper describes the salient design features of these modulators, development of pulse transformers, details of test set-up and discusses the test results of these modulators.

Poster MOPP004 [2.343 MB]

MOPP005

High Power Electron Accelerator Programme at BARC

linac, neutron, experiment, acceleration

58

K.C. Mittal, S. Acharya, R.I. Bakhtsingh, R. Barnwal, D. Bhattacharjee, S. Chandan, N. Chaudhary, R.B. Chavan, S.P. Dewangan, K.P. Dixit, S. Gade, L.M. Gantayet, S.R. Ghodke, S. Gond, D. Jayaprakash, M. Kumar, M.K. Kumar, H.K. Manjunatha, R.L. Mishra, J. Mondal, B. Nayak, S. Nayak, V.T. Nimje, S. Parashar, R. Patel, R.N. Rajan, P.C. Saroj, H.E. Sarukte, D.K. Sharma, V. Sharma, S.K. Srivasatava, N.T. Thakur, A.R. Tillu, R. Tiwari, H. Tyagi, A. Waghmare, V. Yadav
BARC, Mumbai, India

Bhabha Atomic Research Centre in India has taken up the indigenous design & development of high power electron accelerators for industrial, research and cargo-scanning applications. For this purpose, Electron Beam Centre (EBC) has been set up at Navi Mumbai, India. Pulsed RF Linacs, with on-axis coupled cavity configuration, include the 10 MeV Industrial RF linac, as well as 9 MeV linac and compact 6 MeV linac for cargo-scanning applications. Industrial DC accelerators include a 500 keV Cockroft-Walton machine and 3 MeV Dynamitron. Several radiation processing applications, such as material modification, food preservation, flue-gas treatment, etc. have been demonstrated using these accelerators. Cargo-scanning linacs have been successfully commissioned and are being characterized for the required x-ray output. A 30 MeV RF Linac, for research applications, such as shielding studies and n-ToF experiments, is being designed and developed. For ADS studies, a 100 MeV, 100 kW RF Linac system is proposed. This paper presents the details of the design of these accelerators, their development, current status and utilization for various applications.

MOPP007

SF6 Gas Monitoring and Safety for DC Electron Beam Accelerator at EBC, Kharghar, Navi Mumbai

monitoring, high-voltage, operation, experiment

61

S.K. Suneet, S. Acharya, S. Banerjee, R. Barnwal, D. Bhattacharjee, N. Chaudhary, R.B. Chavan, K.P. Dixit, S. Gade, L.M. Gantayet, S.R. Ghodke, S. Gond, B.S. Israel, D. Jayaprakash, N. Lawangare, K. Mahender, R.L. Mishra, K.C. Mittal, B. Nayak, S. Nayak, R. Patel, R.N. Rajan, P.C. Saroj, D.K. Sharma, V. Sharma, M.K. Srvastava, D.P. Suryaprakash, N.T. Thakur, R. Tiwari, A. Waghmare
BARC, Mumbai, India

A 3 MeV, 30kW DC Industrial electron beam accelerator has been designed, commissioned and tested at Electron beam centre, Kharghar. The accelerator has been tested upto 5 kW power level with SF6 gas at 6 kg/cm². The accelerating column, high voltage multiplier column, electron gun and its power supply are housed in accelerator tank, which is filled with SF6 gas as gaseous insulator at 6 kg/cm². The SF6 gas is being used due to high dielectric strength and excellent heat transfer characteristics. The SF6 gas is non toxic and non carcinogenic. The SF6 gas replaces oxygen hence the TLV (threshold limiting value) is 1000 ppm for inhaled gas for persons working on the SF6 gas handling system. The SF6 gas is being green house gas, leak tightness has to monitor in the system and leak if any should be repaired. The gas should be used, recycled and reuse and thus saving the environment. This paper describes the safety and monitoring of the SF6 gas leak, quality and precautions in 3MeV accelerator.

Poster MOPP007 [1.389 MB]

MOPP010

Low Charge State Laser Ion Source for the EBIS Injector

ion, injection, laser, target

64

M. Okamura, J.G. Alessi, E.N. Beebe, T. Kanesue, C.J. Liaw, V. LoDestro, A.I. Pikin, D. Raparia, J. Ritter
BNL, Upton, Long Island, New York, USA
Y. Fuwa, S. Ikeda, M. Kumaki
RIKEN, Saitama, Japan

Funding: NASA
In March 2014, we have successfully commissioned a newly designed low charge high brightness laser ion source (LIS) which delivers various singly charged heavy ions to the electron beam ion source (EBIS) at Brookhaven National Laboratory. Now the LIS is used at routine operation of the RHIC-AGS accelerator complex and is providing stable less-contaminated beams. The laser power density was optimized to provide singly charged ions with low material consumption rate. The nominal laser energy on the target is around 500 mJ with 1064 nm Nd:YAG of the wave length. The induced plasma by the laser is transported through a 3 m pipe to stretch ion beam pulse length to match the EBIS’s requirement and the degradation of the beam current caused by the long drift section of the pipe can be compensated by a longitudinal magnetic filed induced by a coil surrounding the pipe. We also employed a twin laser system to extend the beam width further. At the conference, we will discuss the effect of the new LIS on the various accelerated beams through the EBIS, RFQ and IH-linac.

MOPP012

Beam Commissioning of the SRF 704 MHz Photoemission Gun

cathode, gun, SRF, cavity

70

W. Xu, S.A. Belomestnykh, I. Ben-Zvi, D.M. Gassner, H. Hahn, J.P. Jamilkowski, P. Kankiya, D. Kayran, N. Laloudakis, R.F. Lambiase, G.T. McIntyre, D. Phillips, V. Ptitsyn, K.S. Smith, R. Than, D. Weiss, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi, V. Ptitsyn
Stony Brook University, Stony Brook, USA
D. Holmes
AES, Medford, New York, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
A 704 MHz superconducting RF photoemission electron gun for the R&D ERL project is under comissioning at BNL. Without a cathode insert, the SRF gun achieved its design goal: an accelerating voltage of 2 MV in CW mode. During commissioning with a copper cathode insert it reached 1.9 MV with 18% duty factor, which is limited by mulitpacting in a choke-joint cathode stalk. A new cathode stalk has been designed to eliminate multipacting in the choke-joint. This paper presents recent commissioning results, including cavity commissioning without the cathode stalk insert, first beam commissioning of the SRF gun in pulsed regime, and the design of a multipacting-free cathode stalk.

MOPP013

Vertical Test Results of 704 MHz BNL3 SRF Cavities

cavity, HOM, SRF, damping

73

W. Xu, S.A. Belomestnykh, I. Ben-Zvi, H. Hahn, R. Porgueddu, R. Than, D. Weiss
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi
Stony Brook University, Stony Brook, USA
C.H. Boulware, T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA
M.D. Cole, D. Holmes, T. Schultheiss
AES, Medford, New York, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE, and Award No. DE-SC0002496 to Stony Brook University with the U.S. DOE.
An electron-ion collider (eRHIC) proposed at BNL requires superconducting RF cavities able to support high average beam current. A 5-cell niobium SRF cavity, called BNL3, was designed for a conventional lattice eRHIC design. To avoid inducing emittance degradation and beam-break-up (BBU), the BNL3 cavity was optimized to damp all dangerous higher-order-modes (HOMs) by employing a large beam pipes and coaxial antenna-type couplers. Additionally, the cavity was designed for an acceptable cryogenic load and peak surface RF fields. Two BNL3 cavities have been fabricated and tested at a vertical test facility at BNL. This paper addresses development of the SRF cavities for eRHIC, including SRF cavity design, fabrication and test results.

MOPP015

High Energy Electron Radiography Experiment Research Based on Picosecond Pulse-width Bunch

experiment, linac, proton, quadrupole

76

Q.T. Zhao, S. Cao, R. Cheng, X.K. Shen, Z.M. Zhang, Y.T. Zhao
IMP, Lanzhou, People's Republic of China
Y.-C. Du
TUB, Beijing, People's Republic of China
W. Gai
ANL, Argonne, Illinois, USA

A new scheme is proposed that high energy electron beam as a probe is used for time resolved imaging measurement of high energy density materials, especially for high energy density matter and inertial confinement fusion. The first picosecond pulse-width electron radiography experiment was achieved by Institute of Modern Physics, Chinese Academy of Sciences and Tinghua University (THU), based on THU Linear electron accelerator (LINAC). It is used for principle test and certifying that this kind of LINAC with ultra-short pulse electron bunch can be used for electron radiography. The experiment results, such as magnifying factor and the imaging distortion, are consistent with the beam optical theory well. The 2.5 um RMS spatial resolution has been gotten with magnifying factor 46, with no optimization the imaging lens section. It is found that in the certain range of magnifying factor, the RMS spatial resolution will get better with bigger magnifying factor. The details of experiment set up, results, analysis and discussions are presented here.

Poster MOPP015 [2.866 MB]

MOPP016

Extracting Superconducting Parameters from Surface Resistivity by Using Inside Temperature of SRF Cavities

cavity, accelerating-gradient, SRF, superconductivity

80

G.M. Ge, G.H. Hoffstaetter, M. Liepe, H. Padamsee, V.D. Shemelin
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The surface resistance of an RF superconductor depends on the surface temperature, the residual resistance and various superconductor parameters. These parameters can be determined by measuring the quality factor of a SRF cavity in helium-baths of different temperatures. The surface resistance can be computed from Q0 for any cavity geometry, however it is less simple to determine the temperature of the surface when only the temperature of the helium bath is known. Traditionally, it was approximated that the surface temperature on the inner surface of the cavity is the same as the temperature of the bath. This is a good approximation at small RF-field losses on the surface, but to determine the field dependence of Rs, one cannot be restricted to small field losses. Here we show how computer simulations can be used to determine the inside temperature so that Rs(Tin) can then be used to extract superconductor parameters. The computer code combines the well-known programs HEAT and SRIMP. We find that the error of the incorrect fitting method is about 10% at high RF-fields.

MOPP019

Nb3Sn Materials Studies

niobium, SRF, cavity, ion

92

S. Posen, M. Liepe
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
Th. Proslier
ANL, Argonne, Illinois, USA

Nb₃Sn is a very promising material for use in SRF cavity applications, potentially offering significant improvements in quality factor and energy gradient compared to niobium. In order to better understand how to optimize this material for SRF applications, Nb₃Sn samples were prepared at Cornell via vapor deposition, using varying parameters in the coating process. Microscopic studies were performed with SEM/EDX, and studies were performed on bulk samples to measure secondary electron yield, energy gap, and upper critical magnetic field. The results are presented here, with discussion for how they might point the way towards reaching even higher fields in Nb₃Sn cavities.

Poster MOPP019 [2.742 MB]

MOPP024

Perspectives of the S-Band Linac of FERMI

operation, linac, klystron, FEL

105

A. Fabris, P. Delgiusto, M. Milloch, C. Serpico
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
A. Grudiev
CERN, Geneva, Switzerland

The S-band linac of FERMI, the seeded Free Electron Laser (FEL) located at the Elettra laboratory in Trieste, has reached the peak on-crest electron energy of 1.55 GeV required for FEL-2 with the present layout. Different ways are being considered to extend the operating energy of the S-band linac up to 1.8 GeV. At the same time upgrades on the existing systems are investigated to address the requirements of operability of a users facility. This paper provides an overview of the developments that are under consideration and discusses the requirements and constraints for their implementation.

MOPP025

Longitudinal Beam Profile Measurements in Linac4 Commissioning

rfq, cavity, linac, emittance

108

G. Bellodi, V.A. Dimov, J.-B. Lallement, A.M. Lombardi, U. Raich, F. Roncarolo, F. Zocca
CERN, Geneva, Switzerland
M. Yarmohammadi Satri
IPM, Tehran, Iran

Linac4, the future 160 MeV H⁻ injector to the CERN Proton Synchrotron Booster, is presently under construction at CERN as a central step of the planned upgrade of the LHC injectors. The Linac front-end, composed of a 45 keV ion source, a Low Energy Beam Transport (LEBT), a 352.2 MHz Radio Frequency Quadrupole (RFQ) and a Medium Energy Beam Transport (MEBT) housing a beam chopper, has been installed and commissioned. Precise measurements of the longitudinalμbunch profiles of ion beams were possible with the help of a Bunch Shape Monitor (BSM) developed at INR Moscow. These were crucial for the successful commissioning of the three RF buncher cavities mounted along the MEBT and well complemented with higher precision the information provided in parallel by spectrometer measurements.

MOPP030

CALIFES: A Multi-Purpose Electron Beam for Accelerator Technology Tests

wakefield, acceleration, quadrupole, laser

121

J.L. Navarro Quirante, R. Corsini, W. Farabolini, D. Gamba, A. Grudiev, M.A. Khan, T. Lefèvre, S. Mazzoni, R. Pan, F. Peauger, F. Tecker, N. Vitoratou, K. Yaqub
CERN, Geneva, Switzerland
W. Farabolini, F. Peauger
CEA/DSM/IRFU, France
D. Gamba
JAI, Oxford, United Kingdom
M.A. Khan, K. Yaqub
PINSTECH, Islamabad, Pakistan
J. Ögren, R.J.M.Y. Ruber
Uppsala University, Uppsala, Sweden
N. Vitoratou
Thessaloniki University, Thessaloniki, Greece

The Compact Linear Collider (CLIC) project aims to accelerate and collide electrons and positrons up to 3 TeV center-of-mass energy using a novel two-beam acceleration concept. To prove the feasibility of this technology the CLIC Test Facility CTF3 has been operated during the last years. CALIFES (Concept d’Accélérateur Linéaire pour Faisceau d’Electron Sonde) is an electron linac hosted in the CTF3 complex, which provides a flexible electron beam and the necessary equipment to probe both the two-beam acceleration concept and novel instrumentation to be used in the future CLIC collider. In this paper we describe the CALIFES Linac and its beam characteristics, present recent test results, outline its future program on two-beam module testing and finally discuss about possible future applications as a multi-purpose accelerator technology test facility.

MOPP058

Z-slicer: A Simple Scheme for Electron Beam Current Profile Shaping in a Linac

laser, radiation, dipole, cavity

183

J.C.T. Thangaraj, C.M. Baffes, D.R. Broemmelsiek, D.J. Crawford, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA
W.B. Wortley
University of Rochester, Rochester, New York, USA

Short bunches are a premium at accelerator facilities and their applications include THz generation, short bunch production, shaped bunch production, etc. In this work we report on the design of an experiment involving an electron beam about 50 MeV that will be intercepted by a set of metallic slits inside a bunch compressor. After the mask, some electrons are scattered while other pass through un-affected. After exiting the bunch compressor, those electrons that were not affected by the slits will appear as short electron bunches. The key advantage of our scheme is its simplicity, tunability and low cost. The scheme does not require any additional hardware such as lasers, undulator, transverse deflecting cavity. The tuning variable is only the RF-chirp and detection of the bunching requires just a skew quad in the chicane and a transverse screen downstream. A thermal analysis suggests that MHz operation of the linac can be sustained under certain beam conditions without any damage to the slit mask.

MOPP065

Investigations of Space-Charge Compensation in Low-Energy Beam Transport (LEBT) Sections Using a Particle-in-Cell Code

ion, simulation, proton, space-charge

205

D. Noll, M. Droba, O. Meusel, U. Ratzinger, K. Schulte, C. Wiesner
IAP, Frankfurt am Main, Germany

Among the advantages of magnetostatic LEBT sections is the possibility for compensation of space charge by electrons in the case of positively charged ion beams. In the past, it has been shown that the distribution of these compensation electrons can lead to unwanted emittance growth. However, the distribution of electrons especially in the presence of the magnetic fields of the focussing lenses is difficult to predict. To improve the understanding of the influence on the beam, models for the relevant processes namely residual gas ionization using realistic cross sections as well as secondary electron production on surfaces have been implemented in a particle-in-cell code. In this contribution, we will present the code used as well as first results for two model systems as an example.

MOPP077

Electron-Driven Positron Capture Simulation for ILC

positron, target, linac, booster

233

Y. Seimiya, M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
T. Okugi, T. Omori, M. Satoh, J. Urakawa
KEK, Ibaraki, Japan
T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan

ILC (International Linear Collider) is a next high-energy physics project to study the Higgs property as detail as possible and new phenomena beyond standard model. In ILC, the positron beam is produced by converting gamma rays from undulator radiations. To obtain gamma rays as undulator radiation, the electron beam for collision (150 GeV or more) is used. This positron generation scheme is a totally new approach. From project point of view, it is desirable to have a technical backup as a replacement of the undulator scheme. We propose an ILC positron source based on the conventional electron driven scheme. In this scheme, positron beam is generated from electromagnetic shower in a heavy target material where electron beam is injected. By manipulating the beam time structure to relax the heat load on the production target, the scheme can be feasible technically. In this study, positron capture in the electron driven scheme is simulated from the positron production to the positron damping ring, to demonstrate that an enough amount of positron can be generated and captured with a controllable heat load on the target.

Poster MOPP077 [0.879 MB]

MOPP083

Helical Waveguides for Short Wavelength Accelerators and RF Undulators

undulator, FEL, focusing, radiation

248

S.V. Kuzikov, A.V. Savilov, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia
A.V. Savilov
NNGU, Nizhny Novgorod, Russia

The short wavelength accelerating structure can combine properties of a linear accelerator and a damping ring simultaneously. It provides acceleration of straight on-axis beam as well as cooling of this beam due to the synchrotron radiation of particles. These properties are provided by specific slow eigen mode which consists of two partial waves, TM01 and TM11. The flying RF undulator introduces a high-power short pulse, propagating in a long helically corrugated waveguide where the -1st space harmonic with negative phase velocity is responsible for particle wiggling. High group velocity allows providing long interaction of particles with RF pulse. Calculations show that RF undulator with period 5 mm, undulator parameter 0.1 is possible in 1 GW 10 ns pulse at frequency 30 GHz. The eigen mode in a helical undulator might have 0th harmonic phase velocity equal to light velocity. Such wave can be excited by relativistic drive bunch in the waveguide where witness bunch follows after the drive bunch, wiggles in wakefields, and generates X-rays at whole waveguide length. Helical waveguides can also be used in order to channel low-energy bunches in RF undulator of THz FEL.

Poster MOPP083 [2.139 MB]

MOPP084

Nondestructive Diagnostics of Proton Beam Halo and Transverse Bunch Position by Cerenkov Slow Wave Structures

proton, simulation, diagnostics, monitoring

251

S.V. Kuzikov, M.B. Goykhman, A.V. Gromov, A.V. Palitsin, Yu.V. Rodin, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

An appearance of the halo around bunch of particles is very undesirable destructive phenomenon in high-intensity proton accelerators. We suggest using built-in short BWO section in form of the corrugated metallic waveguide, in order to control particle distribution in real time. In BWO low velocity proton bunch has synchronism with slow spatial harmonic of TM01 wave. Fields of slow harmonic sharply grow in direction from axis to walls and rf power, generated by flying bunch of the given charge, critically depends on transverse bunch size. Results of the simulation, carried out for 20 pC proton bunch of 10 ps duration, show that in 5 GHz BWO of 30 cm length the output rf pulse of several nanosecond duration is varied from mW- level (for 1 mm transverse bunch size) to several tens of mW (for bunch of 20 mm radius). This power level is high enough to control halo appearance in each single proton bunch. The producible rf power in a BWO is also dependent on bunch deflection from axis. This effect we plan to use, in order to provide transverse bunch position monitoring by means of two additional rectangular slow wave section which have corrugations on mutually perpendicular walls.

Poster MOPP084 [0.732 MB]

MOPP086

Ecr Ion Sources Developments at INFN-LNS for the Production of High Brightness Highly Charged Ion Beams

plasma, ion, ion-source, ECRIS

254

D. Mascali, C. Altana, L. Andò, C. Caliri, G. Castro, L. Celona, S. Gammino, L. Neri, F.P. Romano, G. Torrisi
INFN/LNS, Catania, Italy
G. Sorbello
University of Catania, Catania, Italy

The design of future high-performing ECRIS will require alternative approaches in microwave-to-plasma coupling, in order to maximize the electron density at relatively low frequency and reduce the super-hot electrons formation and their consequences on the beam stability and on source reliability. On these purposes, different activities have been carried out at INFN-LNS in the recent past, including advanced modelling, diagnostics, and studies about alternative methods of plasma heating based on electrostatic-waves generation. A description of these activities will be presented, with special emphasis to the microwave to plasma coupling and to the plasma diagnostics. Some of the already collected results have been a basis for the design of the new AISHa source (for hadrontherapy purposes) and the construction of the innovative prototype named Flexible Plasma Trap: on this machine we will search for advanced schemes of microwave launching, now ongoing thanks to full-wave plus kinetic calculations of the wave-to-plasma interaction mechanism

MOPP093

Evaluation of Beam Energy Fluctuations Caused by Phase Noises

linac, experiment, timing, cavity

273

H. Hanaki, H. Dewa, S. Suzuki, K. Yanagida
JASRI/SPring-8, Hyogo-ken, Japan
T. Asaka, T. Ohshima
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

The SSB noises of the RF reference signal dominate the short-term instabilities of the RF phase of the carrier RF. This phase modulation finally results in beam energy fluctuation. This presentation gives a quantitative evaluation of the beam energy fluctuations in an electron linear accelerator caused by phase noises, comparing a theoretical analysis and experimental results. A simple model was introduced to understand how phase noises result in the relative phase difference between a beam bunch and accelerating RF fields. In the experiments, we measured the enhanced beam energy fluctuations by modulating the phase of the reference RF signals with an external signal. The interference between the accelerating RF phase modulation and the timing modulation of a beam bunch was found in the model analysis and also in the experimental results.

MOPP094

Latest Improvements of the SPring-8 Linac for High Reliability

linac, operation, vacuum, injection

276

S. Suzuki, H. Dewa, H. Hanaki, T. Kobayashi, T. Magome, A. Mizuno, T. Taniuchi, K. Yanagida
JASRI/SPring-8, Hyogo-ken, Japan
T. Asaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

In order to perform stable injection to the 8GeV SPring-8 storage ring, which is performing the top-up operation, the high reliability of the linac has been advanced as follows: For reduction of phase variations caused by the waveguide deformation due to the variations of temperature or atmospheric pressure, the waveguide circuit of SF6 enclosure type, which fed RF powers to the bunching section, was replaced with that of vacuum type. And S-band 10MW circulators and isolators of vacuum type were adopted for the first time in the world. The timing system was improved so that the interval time of the beam injection into the 8GeV booster synchrotron and the 1.5 GeV NewSUBARU storage ring has been reduced to 1 sec from 15 seconds, respectively, even in the top-up operation of both storage rings. As a result, the stored current by the top-up operation were further stabilized. The stored current of the NewSUBARU storage ring was stabilized to 0.18% from 0.31%. The electron gun cathode assembly has been developed to reduce the dark emission from a grid plate by the double grid method and the electrolytic polishing.

MOPP095

Emittance Measurement for SPring-8 Linac Using Four Six-Electrode BPMs

emittance, linac, quadrupole, focusing

279

K. Yanagida, H. Hanaki, S. Suzuki
JASRI/SPring-8, Hyogo-ken, Japan

In the SPring-8 linear accelerator (linac) six-electrode beam position monitors (BPMs) have been installed to measure second-order moments. At the end of the linac where the electron beam energy is 1 GeV four quadrupole magnets are utilized for twiss parameter matching toward the following beam transport line. Last year four six-electrode BPMs were installed at the locations of these four quadrupole magnets for an emittance measurement. The relative second-order moments were obtained changing the magnetic field strength of the quadrupole magnets, then beam sizes, emittances and twiss parameters were deduced or calculated. At this time we applied one pair of beam sizes measured by the screen monitor for a precise determination of emittances but we try to implement non-destructive measurement with no screen monitor. Before the emittance measurement a calibration with fifth-order moment correction was carried out changing beam positions at the BPM locations using upstream steering magnets (the entire calibration).

Slides MOPP095 [0.984 MB]

MOPP098

Physical Starting of the First and Second Section of Accelerator Linac-800

undulator, klystron, linac, gun

288

V. Kobets, N. Balalykin, I.N. Meshkov, V. Minashkin, G. Shirkov
JINR, Dubna, Moscow Region, Russia
V. Shabratov
JINR/VBLHEP, Moscow, Russia

In the report discusses the modernization of linear electron accelerator MEA (Medium Energy Accelerator). The aim is to develop a set of MEAs based free-electron lasers, imposed a number of emission wavelengths from infrared to ultraviolet. In work presents the results of the physical starting of the first and second stations accelerating electron linear accelerator LINAC-800, as well as start infrared undulator. We discuss the work program for this accelerator.

MOPP109

Ion Beam Acceleration in Neutron Tube

target, ion, neutron, space-charge

310

V.I. Rashchikov
MEPhI, Moscow, Russia
A.S. Plastun
ITEP, Moscow, Russia

Deuteron beam acceleration in ion-optic system of gas-filled neutron tubes was investigated. PIC code SUMA "*" used for computer simulation of ionization and knock on processes and there influence on deuteron beam parameters. When deuteron and ionized particles own space charge forces become the same order of magnitude as external one, virtual cathode may occurs. It is happened because of injected from ion source deuterons cannot overcome their own space charge potential wall and move in transverse direction. However, electrons, produced by ionization, are trapped within the deuteron beam space charge potential wall and decrease it significantly. Thus, space charge neutralization of deuteron beams by electrons, may considerably increase target current and, as a result, output neutron flow. Moreover, own longitudinal electric field rise near the target leads to reduction of accelerating electrode – target potential wall, which was made to prevent knock on emission from the target. As a result, additional knocked on electrons may appear in the region and should be taken into account. The data obtained were compared with experimental results.
* A.N. Didenko, V.I. Rashchikov, V.E. Fortov, Technical Physics, Vol. 56, No. 10,pp. 1535–1538, 2011

MOPP110

Multipacting Prediction for the 10⁶.1 MHz Quarter Wave Resonator

simulation, cavity, ISAC, experiment

313

M. Gusarova, I.I. Petrushina, E.A. Savin, A.N. Stolbikova
MEPhI, Moscow, Russia
V. Zvyagintsev
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

The results of analytical calculations and numerical simulations of multipacting in the 10⁶.1 MHz Quarter Wave Resonator (QWR) are presented. Resonant voltages, impact energies and corresponding particle trajectories are obtained. In this paper we compare CST PS and MultP-M 3D simulation results for multipacting in the cavity.

MOPP128

Bridging the Gap Between Conventional RF Acceleration and Laser Driven Acceleration

operation, experiment, acceleration, cyclotron

358

M.V. Fazio, V.A. Dolgashev, S.G. Tantawi
SLAC, Menlo Park, California, USA

For decades conventional RF accelerators have been built and operated with ever increasing capability through a few tens of gigahertz in frequency. More recent research takes advantage of the continuing development of high peak power short pulse lasers to drive accelerator structures at optical frequencies. This jump from RF to optical frequencies skips four orders of magnitude in wavelength. With recent experiments that demonstrate high gradients in metallic structures at millimeter wavelengths one is compelled to consider the viability of new approaches for acceleration in the millimeter-wave to terahertz regime. This paper will explore some of these possibilities.

MOPP132

Development of a Micro-Pulse Electron Gun Based Upon pi-Mode Dual-Cavity

cavity, gun, cathode, simulation

367

L. Liao, Q. Gu, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China

The concept of a novel micro-pulse electron gun (MPG) based upon pi-mode dual-cavity is proposed and analyzed in this paper, and we termed it as dual-cavity micro-pulse electron gun (D-MPG) as compared to single-cavity standard MPG. From simulations, it is clear that the D-MPG is capable of yielding dozens of ampere peak currents and a few ps bunch length. Thought the mechanism for dual cavity is not fully understand, the D-MPG has demonstrate the potential to be the injectors for FEL and THz radiation facilities. Also it is a good candidate to replace the thermal cathode for industrial and medical accelerator system because of the cost-effective of the D-MPG.

MOPP138

Fabrication and Measurements of 500 MHz Double Spoke Cavity

cavity, simulation, radiation, target

385

H. Park, J.R. Delayen
JLab, Newport News, Virginia, USA
J.R. Delayen, C.S. Hopper, H. Park
ODU, Norfolk, Virginia, USA

The 500 MHz double spoke cavity has been designed for a high velocity application such as a compact electron accelerator at Center for Accelerator Science at Old Dominion University and is being built at Jefferson Lab. The geometry specific to the double spoke cavity requires a variety of tooling and fixtures. Also a number of joints are expected to make it difficult to maintain the geometric deviation from the design minimal. This paper will report the fabrication technique, resulting tolerance from the design, and comparison between the measurements and simulations.

Poster MOPP138 [2.144 MB]

MOPP140

Simulations for the High Gradient, Low Emittance Supergun RF Photoinjector

emittance, coupling, simulation, gun

391

A.D. Cahill, A. Fukasawa, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
L. Faillace
RadiaBeam, Marina del Rey, California, USA
B. Spataro
INFN/LNF, Frascati (Roma), Italy
A. Valloni
CERN, Geneva, Switzerland

A new S-Band photoinjector is being developed at UCLA that will feature a large accelerating gradient at 160 MeV/m creating a beam with approximately 6.5 MeV at the exit. Because of the large accelerating gradient and other considerations, such as cooling and manufacturing, the new Supergun will be coupled into using a coaxial method, rather than side coupling. With the large accelerating gradient we hope to create very low emittance beams on the order of 0.025 mm mrad. These beams can then be used for a number of purposes, mainly for high quality beams used in FELs. Electric simulations have been done using HFSS and Superfish. Heating and mechanical simulations were done using Ansys. Finally, beam simulations were completed with GPT.

TUIOA03

The MAX IV Linac

linac, gun, storage-ring, injection

400

S. Thorin, J. Andersson, F. Curbis, M. Eriksson, O. Karlberg, D. Kumbaro, E. Mansten, D.F. Olsson, S. Werin
MAX-lab, Lund, Sweden

The MAX IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF). The linac has also been deigned to handle the high demands of an FEL injector. In the storage ring injection mode, the linac is operated at 10 Hz with a thermionic RF gun and the electron bunches are kicked out from the linac at either 3 GeV or 1.5 GeV to reach the respective storage ring. For the Short Pulse mode the linac will operate at 100 Hz with a high brightness photo cathode gun. Compression is done in two double achromats with positive R56 and the natural second order momentum compaction, T566, from the achromats is used together with weak sextupoles to linearise longitudinal phase space, leaving no need for a linearising harmonic cavity. The achromat design for bunch compression produces very short, high peak power electron pulses, while minimizing emittance increase. In this paper we present the MAX IV linac design and the status of commissioning which started in March 2014.

Slides TUIOA03 [4.202 MB]

TUIOA04

The New LCLS-II Project : Status and Challenges

linac, cryomodule, undulator, operation

404

J.N. Galayda
SLAC, Menlo Park, California, USA

The LCLS-II was an upgrade of the LCLS which essentially replicated the LCLS in another tunnel using the middle 1/3 of the SLAC S-band linac. In August 2013, the project was doubled in scope and redirected towards providing MHz-rate X-ray pulses from 0.2 to 5.0 keV while still supporting the ongoing program at the LCLS. The accelerator is now based on a 4.0 GeV SCRF linac installed in the front of the SLAC linac tunnel. Status and challenges of LCLS-II in context of July 2013 recommendation of DOE BESAC for a fully coherent, cw, FEL with photon energies up to ~5 keV.

Slides TUIOA04 [6.386 MB]

TUIOA05

High-Power Industrial Accelerator ILU-14 for E-Beam and X-Ray Processing

cathode, gun, controls, injection

409

V.V. Bezuglov, A.A. Bryazgin, K.N. Chernov, B.L. Faktorovich, V.A. Gorbunov, E.N. Kokin, M.V. Korobeynikov, A.N. Lukin, I. Makarov, S.A. Maximov, A.D. Panfilov, V.M. Radchenko, E.A. Shtarklev, A.V. Sidorov, V.V. Tarnetsky, M.A. Tiunov, V.O. Tkachenko, A. YU. Vlasov, L.A. Voronin
BINP SB RAS, Novosibirsk, Russia

Growing interest to product irradiation by E-beams and X-rays calls for dedicated industrial electron accelerators. BINP has developed ILU-14 radio-frequency pulsed linear accelerator capable of providing 100 kW beam at 7.5-10 MeV. The accelerator has fast removable X-ray converter and can operate both in e-beam and X-ray processing modes. The machine utilizes a low frequency (176 MHz) 6-cells SW accelerating structure. BINP developed this machine as a turn-a-key equipment. Technical details and test results will be presented.

Slides TUIOA05 [4.672 MB]

TUPP006

Design of Relativistic Magnetron for High Power Microwave Generation

simulation, extraction, cathode, cavity

452

R. Chandra, S.R. Ghodke, A.S. Patel, A. Sharma, S.K. Singh
BARC, Mumbai, India

A Linear Induction Accelerator based upon magnetic storage, utilising magnetic switches has been made and it is capable of providing a 400 kV diode voltage, 4 kA beam current for 100 ns pulse duration with 100 Hz repetition rate. It operates in a very high repetition rate due to the use of magnetic switches in it. The lesser shot to shot variation make this system ideal for a Relativistic Magnetron operation, where a huge dependence of output power on applied voltage and applied current is observed. A relativistic magnetron with axial extraction is analytically designed and simulated for this system. This relativistic magnetron is expected to give a power of 100 MW per pulse when operated in its full rating. The design features of this relativistic magnetron are presented here. This magnetron was designed for an output microwave frequency of 2.52 GHz.
*J. Benford, ''Space Applications of High-Power Microwaves'', IEEE Trans. Plasma Sci., vol. 36, no. 3, pp. 569–581, Jun. 2008

TUPP007

Multi Gigawatt High Current Pulsed Electron Accelerator Technology Development Program at BARC

linac, impedance, high-voltage, induction

456

A. Sharma, R. Agarwal, M. Beg, R. Chandra, H. Choudhary, L.M. Gantayet, S.R. Ghodke, TS. Kolge, R. Kumar, S. Mitra, K.C. Mittal, A.S. Patel, A. Roy, P.C. Saroj, K. Senthil, V.K. Sharma, S.K. Singh
BARC, Mumbai, India

High current intense electron beams were investigated earlier for Flash X-rays and nuclear electromagnetic pulse generation. Starting with moderate parameters of 200 kV, 6 kA, 60 ns pulsed electron beam source from a system named Kilo Ampere Linear Injector (KALI-75) our latest development is KALI-30 GW system rated for 1 MV, 30 kA, 80 ns. First repetitive pulse LINAC without spark gap switching was developed as Linear Induction Accelerator (LIA-200) for technology demonstrations at 100 Hz. Also a repetitive Marx generator coupled reflex triode system to operate at 10 Hz. Next to this series of development LIA-400 has been developed to a capacity of 400 kV, 4 kA, 100 ns, 300 Hz. To make these pulse power systems applicable for big LINAC projects like nToF studies or ADS program, a high current electron gun has also been developed to give 100 A, 2 ns,10 Hz pulses.
References
[1].Amitava Roy et al, Journal of App. Physics 103, 2008.
[2].D. D. P. Kumar, et al. Rev. Sci. Inst., vol. 78, no. 11, 2007.
[3].Archana Sharma, et al., IEEE-PS Vol. 39, No. 5, 2011.

TUPP015

Status on Airix Restart

target, induction, timing, operation

462

A. Georges, J. Beaubernard, V. Bernigaud, L. Buche, Y. Collet, S. Combacon, B. Gouin, G. Grandpierre, J.K. Kranzmann, L. Magnin, R. Nicolas, D. Pierre, F. Poulet, Y. Tailleur, J-L. Verstraete, J. Magnan
CEA, Pontfaverger-Moronvilliers, France

The Airix accelerator has been moved from Moronvilliers to Valduc to be part of the EPURE facility. Airix has been refurbished and restarted. This paper presents the first results and quantification of performances at its new location.
*M.Mouillet et al., “First results of AIRIX induction accelerator”,XXth LINAC cf.,p.491(2000)
**H.Dzitko et al., "operationnal efficiency of Airix accelerator since its commissioning",IPAC2012,p.4017

TUPP020

Beam Dynamics Simulation for FLASH2 HGHG Option

simulation, FEL, undulator, radiation

471

G. Feng, S. Ackermann, J. Bödewadt, W. Decking, M. Dohlus, Y.A. Kot, T. Limberg, M. Scholz, I. Zagorodnov
DESY, Hamburg, Germany
K.E. Hacker
DELTA, Dortmund, Germany
T. Plath
Uni HH, Hamburg, Germany

The free electron laser (FEL) facility at DESY in Hamburg (FLASH) is the world's first FEL user facility which can produce extreme ultraviolet (XUV) and soft X-ray photons. In order to increase the beam time delivered to users, a major upgrade named FLASH II is in progress. The electron beamline of FLASH2 consists of diagnostic and matching sections and a SASE undulator section. A seeding undulator section will be installed in the future. FLASH2 will be used as a seeded FEL as well as a SASE FEL. In this paper, some results of beam dynamics simulation for the SASE option are given at first which includes the parameters selection for the bunch compressors, RF parameters calculation for the accelerating modules and the beam dynamics simulation taking into account the collective effects. Beam dynamics simulation for a single stage HGHG option is based on the work for the SASE option. Electron bunches with low uncorrelated energy spread and small energy chirp are obtained after parameters optimization. The FEL simulation results show that 33.6 nm wavelength FEL radiation with high monochromaticity can be seeded at FLASH2 with a 235 nm seeding laser.

TUPP022

RF Tuning of a S-band Hybrid Buncher for Injector Upgrade of LINAC II at DESY

linac, simulation, target, experiment

478

Y.C. Nie, M. Hüning, C. Liebig, M. Schmitz
DESY, Hamburg, Germany

LINACII at DESY currently provides 450 MeV electrons for the synchrotron radiation source PETRAIII. The injector upgrade of it aims to improve its reliability and mitigate the radiological activation due to electron losses at hundreds of MeV. Therefore, a 2.998 GHz hybrid buncher has been developed and will be installed in between a pre-buncher and LINAC II. It comprises a 1-cell standing-wave (SW) section for rapid acceleration and a 13-cells travelling-wave (TW) section for further bunching and acceleration. This paper focuses on its rf tuning procedure. The tuning strategy combines a non-resonant bead-pull measurement of complex electric field and a linear model for local reflection coefficient calculation. The tuning result is satisfying. Field unflatness of the TW section has been improved from ±9% to ±4%, and field in the SW section has been enhanced significantly. By using ASTRA simulation, it has been verified that the residual detuning of the structure is acceptable in view of beam dynamics performance.

TUPP030

Design of a High Average Current Electron Source for the CLIC Drive Beam Injector

gun, cathode, emittance, simulation

493

S. Döbert, N. Chritin
CERN, Geneva, Switzerland
B. Cadilhon, B. Cassany, J. Gardelle, K. Pepitone
CEA, LE BARP cedex, France

The drive beam injector for CLIC needs to deliver a 4.2 A electron beam for a duration of 140 μs with a repetition rate of 50 Hz. The shot to shot and flat top current stability has to be better than 0.1% to guarantee the beam stability required for CLIC. Based on the experience with the CTF3 injector a thermionic high voltage gun with a gridded cathode has been designed together with a sub-harmonic bunching system to achieve these requirements. The grid will allow controlling the current and eventually feedback on the flattop shape. The gun will operate at 140 kV and an emittance of 14 mm mrad can be obtained. The paper describes the design approach and the results of the systematic electromagnetic simulations to optimize the gun. Care was taken during the mechanical design of the gun to obtain a modular design allowing adjusting for different beam currents and cathode sizes.

TUPP034

Commissioning of the CERN LINAC4 Wire Scanner, Wire Grid and Slit-Grid Monitors at 3 and 12 MeV

linac, emittance, space-charge, diagnostics

502

F. Roncarolo, U. Raich, F. Zocca
CERN, Geneva, Switzerland

The CERN LINAC4 has been commissioned up to 12 MeV. The H⁻ beam transverse profile distributions were measured by both wire grids and wire scanners. A slit-grid system located on a temporary diagnostics bench was used to characterize the transverse emittance during the two different stages of commissioning: at the exit of the RFQ (3 MeV) and DTL1 (12 MeV). The wire signal is a balance between the negative charge deposited by the stripped electrons from the H⁻ and the charge lost due to secondary emission. Optimal settings were found for the repelling plates used to suppress secondary emission, which were confirmed by electromagnetic simulations. In addition, suppression of the secondary emission due to the beam space charge was observed. The benefit of changing the wire scanner geometry in order to minimize the cross-talk between horizontal and vertical wires and the observation of thermionic emission on carbon wires are also discussed.

TUPP035

Transverse Profile and Emittance Measurements With a Laser Stripping System During the CERN LINAC4 Commissioning at 3 and 12 MeV

laser, emittance, linac, detector

506

F. Roncarolo, E. Bravin, T. Hofmann, U. Raich, F. Zocca
CERN, Geneva, Switzerland
G.E. Boorman, A. Bosco, S.M. Gibson, K.O. Kruchinin
Royal Holloway, University of London, Surrey, United Kingdom
C. Gabor
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
J.K. Pozimski
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

The CERN LINAC4 beam commissioning at 3 and 12 MeV was completed in 2014. A novel system for measuring the transverse beam profile and emittance, based on low power laser stripping and H⁰ detection using a diamond detector, was successfully tested at these two energies. The measurement results agree with the operational slit-grid method within a few percent in terms of both transverse profile and emittance. After describing the general system setup, this remarkable achievement is discussed in detail together with the present limitations, which will be addressed in order to design a laser based emittance monitor for the LINAC4 top energy of 160 MeV.

TUPP066

Commissioning Results of the 2nd 3.5 Cell SRF Gun for ELBE

gun, SRF, cavity, solenoid

578

A. Arnold, M. Freitag, P. Murcek, J. Teichert, H. Vennekate, R. Xiang
HZDR, Dresden, Germany
G. Ciovati, P. Kneisel, L. Turlington
JLab, Newport News, Virginia, USA

As in 2007 the first 3.5 cell superconducting radio frequency (SRF) gun was taken into operation at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), it turned out that the specified performance to realize an electron energy gain of 9.4 MeV (Epk=50 MV/m @ Q0=10¹⁰) has not been achieved. Instead, the resonator of the gun was limited by field emission to about one third of these values and the measured beam parameters remained significantly behind the expectations. However, to demonstrate the full potential of this new electron source for the ELBE LINAC, a second and slightly modified SRF gun was developed and built in collaboration with Thomas Jefferson National Accelerator Facility (TJNAF). We will report on commissioning and first results of this new SRF gun. This includes in particular the characterization of the most important RF properties of the cavity as well as their comparison with previous vertical test results.

Poster TUPP066 [1.220 MB]

TUPP078

High Gain FEL with a Micro-bunch Structured Beam by the Transverse-Longitudinal Phase Space Rotation

FEL, cavity, radiation, cathode

607

M. Kuriki, Y. Seimiya
HU/AdSM, Higashi-Hiroshima, Japan
H. Hayano, K. Ohmi
KEK, Ibaraki, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
R. Kato
ISIR, Osaka, Japan

FEL is one of the ideal radiation source over the wide range of wavelength region with a high brightness and a high coherence. Many methods to improve FEL gain has been proposed by introducing an active modulation on the bunch charge distribution. The transverse-longitudinal phase-space rotation is one of the promising method to realize the density modulation as the micro-bunch structure. Initially, a beam density modulation in the transverse direction made by a mechanical slit, is properly transformed into the density modulation in the longitudinal direction by the phase-space rotation. That results the longitudinal micro-bunch structure. The micro-bunch structure made with this method has a large tunability by changing the slit geometry, the beam line design, and the beam dynamics tuning. A compact FEL facility based on this method is proposed.

Poster TUPP078 [0.594 MB]

TUPP086

RAON Superconducting Radio Frequency Test Facility Construction

cavity, radiation, cryogenics, SRF

625

H. Kim, D. Jeon, Y.W. Jo, Y. Jung, S.A. Kim, W.K. Kim, S.J. Lee, S.W. Nam, G.-T. Park, J.H. Shin
IBS, Daejeon, Republic of Korea

Superconducting Radio Frequency (SRF) test facility for RAON is under construction process. It consists of cryogenic system, clean room for cavity process and assembles vertical test, horizontal test, and the radiation shield. The cryoplant has 330 W (4.5 K equivalent) which supplies 4.5K supercritical helium to the cavity test and cryomodule test bench. Clean rooms are for cavity process and assemble whose class is from 10 to 10000. The layout for the vertical and horizontal test bench is shown and the radiation shield for the test bench is shown to reduce X-ray coming from cavity. To estimate the thickness of concrete, radiation simulation is performed.

TUPP088

The Fabrication of the β=0.12 HWR at RISP

niobium, cavity, target, vacuum

628

G.-T. Park, H.J. Cha, Y. Jung, H. Kim, W.K. Kim
IBS, Daejeon, Republic of Korea

At RISP, the superconducting cavities have been developed to construct RAON, the heavy ion accelerator. Among the cavities, the fabrication of the QWR (Quarter wave resonator) and the HWR (Half wave resonator)are complete. The detailed fabrication processes including material inspection, forming, the electron beam welding, and the clamp up test are described.

TUPP091

3 BPM Study at PAL ITF

controls, pick-up, laser, interface

637

M. Žnidarčič
I-Tech, Solkan, Slovenia
C. Kim, S.J. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

Pohang Accelerator Laboratory (PAL) is building the 4th generation X-ray free electron laser (XFEL) machine. To examine the efficiency of various diagnostic devices an injector test facility (ITF) was constructed. The last part of the ITF is dedicated for evaluation of beam position measurement devices. A “3-BPM-study” was done with 3 Libera Single Pass E BPM modules that were connected to the 3 equidistantly positioned stripline sensors. The aim of the test was to measure the performances of the Libera Single Pass E devices with beam conditions similar to the real pal XFEL machine.

TUPP096

LUE-200 Linac. Status & Development

klystron, neutron, linac, beam-loading

653

A.P. Sumbaev, A.S. Kayukov, V. Kobets, V. Minashkin, V.G. Pyataev, V.A. Shvets
JINR, Dubna, Moscow Region, Russia
V. Shabratov
JINR/VBLHEP, Moscow, Russia
V.N. Shvetsov
JINR/FLNP, Moscow Region, Russia

The general scheme and current status of an electron linear accelerator with an S-band travelling wave (f = 2856 MHz) accelerating structure – a driver for a pulsed neutron source (IREN) at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research - are presented. The parameters of the accelerating system and the measured parameters of the electron beam – pulse-beam current, duration of the current pulse, repetition rate, electron-energy spectrum, and loading characteristics of the accelerating structure - are given. The beginning of the implementation of the project of the second stage of the IREN facility, which forms the basis for the development of the accelerator aimed at increasing its beam power, is reported. Technical solutions underlying the modernization of the accelerator’s electrophysical systems are discussed: accelerating system, RF power supplies,and modulators.

TUPP110

Quasi Nonlinear Plasma Wakefield Acceleration Experiments

plasma, focusing, experiment, emittance

680

S.K. Barber, G. Andonian, B.D. O'Shea, J.B. Rosenzweig, Y. Sakai, O. Williams
UCLA, Los Angeles, USA
M. Ferrario
INFN/LNF, Frascati (Roma), Italy
P. Muggli
MPI, Muenchen, Germany

It is generally agreed that the best way forward for beam driven plasma wakefield acceleration (PWFA) is in the nonlinear or blowout regime. In this regime the expulsion of the plasma electrons from the beam occupied region produces a linear transverse focusing effect and position independent longitudinal accelerating fields, which can, in principle, produce high quality beams accelerated over many meters. However, certain aspects of a linear plasma response can be advantageous, such as the possibility for resonant excitation of wakefields through the use of pulse trains. Exploiting advantages of both linear and nonlinear PWFA may be achievable through the use of low emittance and tightly focused beams with relatively small charge. In this case the beam density can be greater than that of the ambient plasma while simultaneously having a smaller total charge than the plasma electrons contained in a cubic plasma skin depth allowing for blowout in the region of the beam while simultaneously maintaining a quasi linear response in the bulk plasma. Recent experiments at BNL have been aimed at probing various salient aspects of this regime and are presented here.

TUPP111

SwissFEL C-band LLRF Prototype System

LLRF, controls, feedback, klystron

683

A. Hauff, M. Broennimann, I. Brunnenkant, A. Dietrich, Z. Geng, F. Gärtner, M. Jurcevic, R. Kalt, S. Mair, A. Řežaeizadeh, L. Schebacher, T. Schilcher, W. Sturzenegger
PSI, Villigen PSI, Switzerland

SwissFEL is driven by more than 30 RF stations at different frequencies (S-, C-, X-band). To control the RF a new, in-house developed digital Low Level RF (LLRF) system measures up to 24 RF signals per station and performs a pulse-to-pulse feedback at a repetition rate of 100 Hz. The RF signals are down-converted to a common intermediate frequency. The state-of-the-art digital processing units are integrated into the PSI’s EPICS controls environment. Emphasis has been put on modularity of the system to provide a well-defined path for upgrades. Thus the RF front ends are separated from the digital processing units with their FMC standard interfaces for ADCs and DACs. A first prototype of the LLRF system consisting of the digital back end together with a C-band RF front end was installed in the SwissFEL C-band test facility. In this report the performance of the prototype system has been compared with the LLRF system requirements for SwissFEL. The critical parameters are high intra-pulse phase and amplitude resolutions, good channel-to-channel isolations, very low phase to amplitude modulation and a negligible temperature drift.

TUPP120

Commissioning of BINP Injection Complex VEPP-5

injection, dumping, positron, closed-orbit

702

A.A. Starostenko, A.E. Levichev, D.A. Nikiforov
BINP SB RAS, Novosibirsk, Russia

New BINP injector complex VEPP-5 consist of S-band linear accelerators (270 and 420MeV), positron converter (at 270 MeV) and damping ring. The injector complex will provide e⁺/e⁻ particles for the 2 colliders at BINP - VEPP-4M and VEPP-2000. After a long construction period the injector is in its commissioning stage now. Positron rate production of 6·10⁸ positrons/pulse and conversion yield of 0.14/GeV and stored positron beam current of 70mA were already achieved.

TUPP121

Limitations for Acceleration of Intermediate Mass Particles with Traveling Wave Structure

operation, acceleration, accelerating-gradient, linac

705

V.V. Paramonov
RAS/INR, Moscow, Russia

The Disk Loaded Waveguide (DLW) is the mostly used high frequency structure for acceleration of lightweight particles – electrons in the high energy range. DLW parameters are considered for the lower frequency range and lower particle velocity. Physical and technical restrictions for DLW application for the low particles velocity are analyzed. Basing on particularities of acceleration with traveling wave, deep optimization of DLW cells dimensions, the choice of optimal operating phase advance for each DLW section and combination of forward and backward wave modes, it looks possible to create the simple, cost effective acceleration system for intermediate particles acceleration in the moderate velocity range, in some parameters overcoming accelerating system with RF cavities in the standing wave mode.

TUPP123

Design of Novel RF Sources to Reduce the Beam Pace-Charge Effects

cavity, klystron, space-charge, cathode

712

M. Dal Forno, A. Jensen, R.D. Ruth, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: DOE
Traditional RF sources, such as Klystrons, TWT require a magnet (such as a solenoid) in order to maintain the electron beam focusing, compensating the particle repulsion caused by space charge effects. We designed a novel RF source with an alternative approach that reduces beam space charge problems. This paper shows the design of the device, with a new formulation of the Child’s Law, and the mode-beam stability analysis. The electron beam interaction with the cavity fields has been analyzed by means of particle tracking software in order to evaluate the beam bunching and the beam dynamics.

Poster TUPP123 [0.172 MB]

TUPP128

ECHO-enabled Tunable Terahertz Radiation Generation with a Laser-modulated Relativistic Electron Beam

laser, radiation, FEL, simulation

719

D. Huang, Q. Gu, Z. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
D. Xiang
Shanghai Jiao Tong University, Shanghai, People's Republic of China

A new scheme to generate narrow-band tunable Terahertz (THz) radiation using a variant of the echo-enabled harmonic generation is analyzed. We show that by using an energy chirped beam, THz density modulation in the beam phase space can be produced with two lasers having the same wavelength. This removes the need for an optical parametric amplifier system to provide a wavelength-tunable laser to vary the central frequency of the THz radiation. The practical feasibility and applications of this scheme is demonstrated numerically with a start-to-end simulation using the beam parameters at Shanghai Deep Ultraviolet Free-Electron Laser facility (SDUV). The central frequency of the density modulation can be continuously tuned by either varying the chirp of the beam or the momentum compactions of the chicanes. The influence of nonlinear RF chirp and longitudinal space charge effect have also been studied in our article. We also briefly discuss how one may retrieve the beam longitudinal phase space through measurement of the THz density modulation. \end{abstract}

TUPP133

Optimization of the RF Cavity of the Medical Purpose Electron Linac by Using Genetic Algorithm

cavity, impedance, linac, acceleration

726

S. Shin, J.-S. Chai
SKKU, Suwon, Republic of Korea

A compact electron linear accelerator for the medical application has been developing at Sungkyunkwan University. Due to this electron linac is attached on the robot arm or gantry, it should be compact enough to be held by the structure. An X-band technology has been used to meet the requirements for the compact linac. Because the particle accelerator is complex and sensitive machine to design it takes a lot of time to get a good performance accelerator. In this research, a special technique named single-objective genetic algorithm for the optimization process has been applied to achieve a better RF cavity design by changing various geometric parameters.

TUPP135

Beam Dynamics Calculations and Magnet Design for Future Measurements of Transverse Beam Break-Up at the S-DALINAC*

linac, experiment, recirculation, sextupole

729

F. Hug, M. Arnold, L.E. Jürgensen, T. Kürzeder, N. Pietralla, M. Schilling
TU Darmstadt, Darmstadt, Germany

Funding: *Work supported by the BMBF through 05K13RDA
The superconducting electron accelerator S-DALINAC at TU Darmstadt produces c.w. electron beams of up to 90 MeV. The S-DALINAC consists of a SC 14-MeV injector linac, a SC main linac and two recirculation paths. Currently a third recirculation is in its final design phase and will be constructed end 2014 in order to achieve an energy of 130 MeV in future. The main linac houses eight 20-cell SRF cavities operated at 3 GHz and 2 K. Due to the occurance of transverse beam break-up, the highest stable beam current obtained so far amounts to 5 μA only, which is below the design beam current of 20 μA but sufficient for the nuclear physics experiments carried out at Darmstadt since 1991. In this work we will present beam-dynamics calculations and newly designed magnets for planned experiments at the S-DALINAC in order to benchmark different strategies of increasing the threshold current for beam break-up.

TUPP140

Observation of >GV/m Decelerating Fields in Dielectric Lined Waveguides

wakefield, radiation, vacuum, experiment

743

B.D. O'Shea, G. Andonian, K.L. Fitzmorris, S. Hakimi, J. Harrison, J.B. Rosenzweig, O. Williams
UCLA, Los Angeles, California, USA
M.J. Hogan, V. Yakimenko
SLAC, Menlo Park, California, USA

Recent experimental measurements of the energy lost to wakefields in a dielectric lined waveguide are presented. These measurements demonstrate average decelerating gradients on the order of >1 GV/m, for two different structures. The measurements were made at the Facility for Advanced aCcelerator Experimental Tests (FACET) at SLAC National Laboratory using sub-millimeter diameter fifteen-centimeter long quartz fibers of annular cross section. The unique extremely short, high charge, ultra relativistic beam at FACET (200 fs, 3 nC, 20 GeV) allows the use of dielectric wakefield structures of unprecedented size and length. In addition to experimental results, we support conclusions with simulation and theoretical work. This measurement builds on a large body of work previously performed using dielectric wakefield structures in an effort to provide high gradient accelerating structures for tomorrows linear colliders.

WEIOA04

Phase Locked Magnetrons for Accelerators

injection, cathode, controls, cavity

751

A.C. Dexter
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

Magnetrons offer lower capital costs and higher efficiencies than klystrons, however are natural oscillators rather than amplifiers. This paper reviews techniques and issues for applying high efficiency L band magnetrons to long pulse, high intensity proton linacs. Reference is made to a proof of principle experiment whereby the phase of an SRF cavity was accurately controlled when energised by a magnetron.

Slides WEIOA04 [1.224 MB]

THIOB03

Results From the LCLS X-Band Transverse Deflector With Femtosecond Temporal Resolution

FEL, undulator, photon, diagnostics

819

Y. Ding, F.-J. Decker, V.A. Dolgashev, J.C. Frisch, Z. Huang, P. Krejcik, H. Loos, A. Lutmann, A. Marinelli, T.J. Maxwell, D.F. Ratner, J.L. Turner, J.W. Wang, M.-H. Wang, J.J. Welch, J. Wu
SLAC, Menlo Park, California, USA
C. Behrens
DESY, Hamburg, Germany

An X-band RF transverse deflector composed of two 1-m-long X-band deflecting structures has been recently commissioned at the Linac Coherent Light Source (LCLS) at SLAC National Accelerator Laboratory. Located downstream of the FEL undulator, this device provides electron beam longitudinal phase space diagnostics in both time and energy which enables reconstruction of the X-ray FEL power profiles with an unprecedented resolution. This talk reports on the progress of this new LCLS X-band transverse deflector, first usage experience and measured results.

Slides THIOB03 [3.508 MB]

THIOC02

Allison Scanner Emittance Diagnostic Development at TRIUMF

emittance, ion, gun, TRIUMF

829

A. Laxdal, F. Ames, R.A. Baartman, W.R. Rawnsley, A. Sen, V.A. Verzilov, G. Waters
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
R.V. Hariwal
IUAC, New Delhi, India
M. Kownacki
SFU, Burnaby, BC, Canada
R.F. Paris
University of Ottawa, Ottawa, Ontario, Canada

TRIUMF has developed Allison scanners to measure the transverse emittance of both low intensity hadron beams at 10⁴ pps and high intensity electron beams at 10mA for a dynamic range of more than 10¹² in intensity. The devices give high resolution transverse emittance information in a compact package that fits in a single diagnostic box. The talk will present the design and performance of the operating devices.

Slides THIOC02 [2.349 MB]

THPP003

Cooling of High Pressure Insulating Gas for 3 MeV DC Accelerator: an Alternate Approach

controls, high-voltage, resonance, interlocks

839

S.R. Ghodke, S. Acharya, R. Barnwal, K.P. Dixit, L.M. Gantayet, B.S. Israel, D. Jayaprakash, K. Mahender, K.C. Mittal, S. Nayak, R.N. Rajan, D.K. Sharma, V. Sharma, S.K. Suneet, D.P. Suryaprakash
BARC, Mumbai, India

3 MeV Accelerator Project working inside the ‘Electron Beam Centre’ (EBC) building at Kharghar, Navi Mumbai. Generally in DC and Pelletron accelerators Nitrogen/SF6 gas is taken out from accelerator tank and it is cooled by separate heat exchanger and blower unit outside the accelerator tank. In our alternate approach we have designed fan/ blower to work under high pressure inside accelerator tank. Fans are designed to work in high pressure SF6 environment at 7 bar absolute pressure with 42 kg/m3 SF6 gas density. Fan throughs air over radiator type finned tube heat exchanger, installed inside accelerator tank. Fan speeds are controlled through variable frequency drive. Two numbers of such assemblies are fabricated, installed and tested in Nitrogen and SF6 gas environment at different pressure and variable fan speed. Performances are recorded and plotted in graphical form. These cooling systems are shown excellent performance in last five years. Paper will discuss about design of cooling system, cooling calculation of fan, fabrication of fan and heat exchanger, 5 TR chiller unit, variable frequency drive, fan performance etc.

Poster THPP003 [1.644 MB]

THPP004

Design, Development and Initial Results of Solid State Magnetron Modulator

distributed, klystron, induction, impedance

843

A.R. Tillu, S. Chandan, K.P. Dixit, K.C. Mittal, H.E. Sarukte
BARC, Mumbai, India

A prototype solid state pulse modulator based on Induction Adder Topology has been designed ans is currently being tested on a S Band Pulsed magnetron rated for 3.2M W Peak RF Power. After successful lab tests the modulator is intended for use in cargo scanning and radiography applications. Currently the topology consists of 4 no.s of single turn primaries driven independently at voltages not more than 1000V. The secondary encircles all the four primaries to generate the desired pulsed voltage across the magnetron. The designed output pulse parameters are 50k V, 120A, 4micro s, at a pulse repetition rate of 250 pps. The paper describes the design and development of the Epoxy Cast Pulse transformer and the Low Inductance Primary Circuit. The rise time measured was < 400ns, and the reverse voltage at the end of the pulse was less than 12kV (at 43k V pulse). The testing was done at low PRF, on two different magnetrons having different operating points to demonstrate fairly good impedance independent operating characteristic of the magnetron modulator. Initial test results on the Resistive load and Magnetron load will also be discussed

Poster THPP004 [1.575 MB]

THPP005

A New High Current and Single Bunch Injector at ELSA

booster, linac, injection, timing

847

M. Schedler, P. Hänisch, W. Hillert, D. Proft
ELSA, Bonn, Germany
J. Zappai
Uni Bonn, Bonn, Germany

At the Electron Stretcher Facility ELSA of Bonn University, an increase of the maximum stored beam current from 20 mA to 200 mA is planned for the stretcher ring. In order to keep the desired duty cycle of the post acceleration mode at about 80 \% a new high current injector operating at 3 GHz has been built. It provides an electron beam with an energy of 20 MeV and a beam current of 800 mA in pulsed operation. A prebuncher, travelling wave buncher system and an energy compressing system are installed in order to enhance the beam acceptance of the linac and to reduce the energy spread in order to achieve an improved injection efficiency into the booster synchrotron. For studying accelerators impedances and beam instabilities the linac is able to produce single bunches with a pulse current of 2 A which will be accumulated in the stretcher ring.

THPP012

A Prototype 1 Mev X-Band Linac for Aviation Cargo Inspection

cavity, linac, simulation, accelerating-gradient

853

M. Jenkins, P.K. Ambattu, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
S. Andrews, T.A. Cross, C.R. Weatherup
e2v, Chelmsford, Essex, United Kingdom
P.A. Corlett, P. Goudket, A.R. Goulden, P.A. McIntosh, K.J. Middleman, Y.M. Saveliev, R.J. Smith, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S.A. Griffiths, M.D. Hancock, T. Hartnett, C. Hill, J.P. Hindley, B.G. Martlew, N. Templeton
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

Aviation cargo Unit Load Device (ULD) containers are typically much smaller than standard shipping containers, with a volume of around 1m3. Standard 3-6 MeV X-ray screening linacs have too much energy to obtain sufficient contrast when inspecting ULD’s, hence a lower 1 MeV linac is required. In order to obtain a small physical footprint, which can be adapted to mobile platform applications a compact design is required, hence X-band technology is the ideal solution. A prototype 1 MeV linac cavity has been designed by Lancaster University, manufactured by Comeb (Italy) and tested at STFC Daresbury Laboratory using an e2v magnetron, modulator and electron gun. The cavity is a bi-periodic π/2 structure, with beam-pipe aperture coupling to simplify the manufacture at the expense of shunt impedance. The design, manufacture and testing of this linac structure is presented.

THPP028

Design and Beamloading-Simulations of a Pre-Bunching Cavity for the CLIC Drive Beam Injector

cavity, beam-loading, simulation, coupling

895

M. Dayyani Kelisani, S. Döbert, H. Shaker
CERN, Geneva, Switzerland
H. Shaker
IPM, Tehran, Iran

The CLIC project is developing a multi-TeV center-of-mass electron-positron collider based on high-gradient, room-temperature accelerating structures and a novel two-beam RF power generation scheme. The RF power for the CLIC accelerating structures is provided by the so-called drive beam which is a low energy, high current electron beam. The drive beam will be generated from a high current (up to 5 A) pulsed (142μs) thermionic electron gun and then followed by a bunching system. The bunching system is composed of three sub-harmonic bunchers operating at a frequency of 499.75 MHz, a pre-buncher and a traveling wave buncher both operating at 999.5MHz. The pre-buncher cavity, which has a great importance on minimization the satellite population, should be designed with special consideration of the high beam loading effect due to the high current beam crossing the cavity. In this work we report on RF design, analytical beam loading calculations and simulations for the CLIC drive beam injector pre-buncher cavity.

THPP031

Plans for an ERL Test Facility at CERN

cavity, cryomodule, SRF, linac

905

E. Jensen, O.S. Brüning, R. Calaga, K.M. Schirm, R. Torres-Sanchez, A. Valloni
CERN, Geneva, Switzerland
K. Aulenbacher
IKP, Mainz, Germany
S.A. Bogacz, A. Hutton
JLab, Newport News, Virginia, USA
M. Klein
The University of Liverpool, Liverpool, United Kingdom

The baseline electron accelerator for LHeC and one option for FCC-he is an Energy Recovery Linac. To prepare and study the necessary key technologies, CERN has started – in collaboration with JLAB and Mainz University – the conceptual design of an ERL Test Facility (ERL-TF). Staged construction will allow the study under different conditions with up to 3 passes, beam energies of up to about 1 GeV and currents of up to 50 mA. The design and development of superconducting cavity modules, including coupler and HOM damper designs, are also of central importance for other existing and future accelerators and their tests are at the heart of the current ERL-TF goals. The ERL-TF could also provide a unique infrastructure for several applications that go beyond developing and testing the ERL technology at CERN. In addition to experimental studies of beam dynamics, operational and reliability issues in an ERL, it could equally serve for quench tests of superconducting magnets, as physics experimental facility on its own right or as test stand for detector developments. This contribution will describe the goals and the concept of the facility and the status of the R&D.

THPP035

Deceleration Measurements of an Electron Beam in the CLIC Test Facility 3

lattice, quadrupole, acceleration, linear-collider

920

R.L. Lillestøl, S. Döbert
CERN, Geneva, Switzerland
E. Adli
University of Oslo, Oslo, Norway

The Test Beam Line at the CLIC Test Facility 3 at CERN is a proof-of-principle of the future CLIC decelerators, which will extract a large amount of beam energy for acceleration of the main CLIC beams. The current beamline consists of a FODO lattice with 13 Power Extraction and Transfer Structures (PETS). We discuss beam deceleration measurements of up to 37 %, taking into account effects from the bunch length and the bunch phase. The 12 GHz phase is reproduced based on measurements in a PETS with an uncombined beam. The spectrometer measurements are also compared to predictions based on the beam current and on the produced rf power in the PETS, as well as particle tracking simulations with the Placet code.

THPP038

The Drift Tube Welding Assembly for the Linac4 Drift Tube Linac at CERN

linac, operation, drift-tube-linac, DTL

929

I. Sexton, A. Cherif, Y. Cuvet, G. Favre, J.-M. Geisser, S. Ramberger, S. Sgobba, T. Tardy
CERN, Geneva, Switzerland
F.M. Mirapeix
DMP, Mendaro, Spain

The fabrication of the Linac4 Drift Tube Linac (DTL) required the welding assembly of 10⁸ drift tubes (DT) which has been undertaken at the CERN workshop. The design of the DTL is particular in that it was purposely simplified to avoid any position adjustment mechanism for drift tubes in the tank. In consequence, drift tubes have been designed with tight tolerances and parts have been assembled with an optimised welding procedure. Two re-machining stages have been introduced in order to compensate for welding distortions. This paper discusses the various assembly stages with a view on the final precision that has been achieved.

Poster THPP038 [8.665 MB]

THPP039

Electron Beam Welding and Vacuum Brazing Characterization for SRF Cavities

vacuum, niobium, cavity, interface

932

N. Valverde Alonso, S. Atieh, I. Aviles Santillana, S. Calatroni, O. Capatina, L.M.A. Ferreira, F. Pillon, M. Redondas Monteserin, T. Renaglia, K.M. Schirm, T. Tardy, A. Vacca
CERN, Geneva, Switzerland

In the framework of the SPL R&D effort at CERN, development design efforts study the joining of dissimilar metals: bulk niobium for the superconducting RF cavities and stainless steel (316LN) or titanium alloys (Ti-6Al-4V and Nb55Ti) for the cryostats. Joining techniques of electron beam welding (EBW) and vacuum brazing are particularly important for these applications. These processes have been used in the accelerator community and developed into generally accepted “best practice”. Studies were performed to update the existing knowledge, and comprehensively characterise these joints via mechanical and metallurgical investigations using modern available technologies. The developed solutions are described in detail, some currently being applied uniquely at CERN.

Poster THPP039 [5.324 MB]

THPP055

High Power Density Test of PXIE MEBT Absorber Prototype

simulation, radiation, experiment, focusing

973

A.V. Shemyakin, C.M. Baffes
Fermilab, Batavia, Illinois, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the United States Department of Energy
One of the goals of the PXIE program at Fermilab is to demonstrate the capability to form an arbitrary bunch pattern from an initially CW 162.5 MHz H⁻ bunch train coming out of an RFQ. The bunch-by-bunch selection will take place in the 2.1 MeV Medium Energy Beam Transport (MEBT) by directing the undesired bunches onto an absorber that needs to withstand a beam power of up to 21 kW, focused onto a spot with a ~2 mm rms radius. Two prototypes of the absorber were manufactured from molybdenum alloy TZM, and tested with a 28 keV DC electron beam up to the peak surface power density required for PXIE, 17W/mm2. Temperatures and flow parameters were measured and compared to analysis. This paper describes the absorber prototypes and key testing results.

THPP058

A Review of Emittance Exchanger Beamlines: Past Experiments and Future Proposals

cavity, emittance, laser, experiment

982

J.C.T. Thangaraj
Fermilab, Batavia, Illinois, USA

Emittance exchangers (EEX) are advanced phase space manipulation schemes where the transverse phase space of the electron beam is exchanged with the longitudinal phase space. The first experimentally demonstrated concept of the emittance exchanger at the A0 photoinjector at Fermilab used a transverse deflecting cavity (TDC) sandwiched between two doglegs. In this talk, I will briefly review the history of the emittance exchange beamline experiments from a low charge beam without RF chirp to a high charge beam with RF chirp including collective effects such as coherent synchrotron radiation. I will also describe how shaping application have been spawned based on EEX. I will then review future schemes that has been proposed and propose two additional schemes of EEX that can be implemented in existing modern linacs. As an example, we present an improved emittance exchanger scheme that uses a TDC sandwiched between two chicanes. The significant advantage of this scheme is that it allows the use of the expensive transverse deflecting cavity for diagnostics and still allows the flexibility to use the existing beamline either as a bunch compressor or an emittance exchanger.

THPP059

Z-Shaper: A Picosecond UV Laser Pulse Shaping Channel at the Advanced Superconducting Test Accelerator

laser, experiment, linac, controls

986

J.C.T. Thangaraj, D.R. Edstrom, A.H. Lumpkin, J. Ruan
Fermilab, Batavia, Illinois, USA
B. Beaudoin
UMD, College Park, Maryland, USA

Many accelerator applications require a longitudinally shaped electron beam profile for studies ranging from THz generation to dielectric wakefield acceleration. An electron beam profile can be shaped through many techniques in both electron beam generation, such as with a DAZZLER or in ellipsoidal pulse generation, and beam transport, using an emittance exchanger or linearizing harmonic cavity. In this paper, shaping of a UV pulse with length on the order of picoseconds is examined using alpha-BBO crystals in the Advanced Superconducting Test Accelerator (ASTA) drive laser. A relatively economical solution to effect a predictable and tunable longitudinal bunch shape, profiles have been generated and observed using a Hamamatsu C5680 streak camera, and the results are compared with the analytical theory.

THPP075

Development of Superconducting Spoke Cavity for Electron Accelerators

cavity, simulation, multipactoring, acceleration

1030

T. Kubo, T. Saeki
KEK, Ibaraki, Japan
E. Cenni, H. Fujisawa, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
R. Hajima, M. Sawamura
JAEA, Ibaraki-ken, Japan

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We have launched a development program of a superconducting spoke cavity for electron acceleration, in order to realize a compact industrial-use X-ray source with the laser-Compton scattering. Efforts for optimizing a cavity design by the electromagnetic field simulation, tracking of multipactor electrons and mechanical property calculations have been continued so far. The optimization processes reached the final stage, and studies toward fabrication processes started. In this presentation, we will show results and processes of the optimization. Attempts to fabricate the spoke cavity, which have just begun, will also be presented.

THPP084

Cyclotron-Undulator Cooling of Electron Beams

undulator, cyclotron, FEL, simulation

1041

S.V. Kuzikov, I.V. Bandurkin, A.V. Savilov
IAP/RAS, Nizhny Novgorod, Russia
A.V. Savilov
NNGU, Nizhny Novgorod, Russia

XFELs require high-quality electron beams which can be produced in damping rings. For XFEL, based on Compton scattering of laser light, instead of the damping ring we consider a new compact device where electrons move in the undulator with axial DC magnetic field. In this undulator electrons move near resonant condition, rotating with cyclotron frequency and wiggling at similar bounce frequency. Such undulator allows compensation of the initial velocity spread by perturbations of the longitudinal velocities caused by transverse wiggling. Calculation show that ~1% velocity spread of 5 MeV electron beam (typical for photoinjectors) can be reduced to ~0.01% at distance as long as 20 undulator periods. In the advanced scheme, where the described undulators alternate with sections of the cyclotron radiation, energy spread as small as 0.001% is reachable. Calculations show that this principle works also for high energy beams (100 MeV and more), where RF undulator instead of DC-magnet undulator is preferable.

Poster THPP084 [0.713 MB]

THPP096

RF Coaxial Resonator for Investigating Multipactor Discharges on Metal and Dielectric Surfaces

multipactoring, vacuum, experiment, coupling

1074

M. El Khaldi, W. Kaabi, P. Lepercq, Y. Peinaud
LAL, Orsay, France

Multipactor discharge is a phenomenon in which electrons impact one or more material surfaces in resonance with an alternating electric field. The discharge can occur for a wide range of frequencies, from the MHz range to tens of GHz, and in wide array of geometries if the impacted surface has a secondary electron emission (SEE) yield larger than one. The discharge can take place on a single surface or between two surfaces. A novel coaxial resonator to investigate two-surface multipactor discharges on metal and dielectric surfaces in the gap region under vacuum conditions has been designed and tested. The resonator is ~ 100 mm in length with an outer diameter of ~ 60 mm (internal dimensions). A pulsed RF source delivers up to 30 W average power over a wide frequency range 650-900 MHz to the RF resonator. The incident and reflected RF signals are monitored by calibrated RF diodes. An electron probe provides temporal measurements of the multipacting electron current with respect to the RF power. These experiments were successful in identifying multipacting and allowed us the evaluation of a home made sputtered titanium nitride (TiN) thin layers as a Multipactor suppressor.

THPP100

Result of MHI 2-Cell Seamless Dumb-Bell Cavity Vertical Test

cavity, superconducting-cavity, linac, vacuum

1087

K. Okihira, H. Hara, N. Ikeda, F. Inoue, K. Sennyu
MHI, Kobe, Japan
R.L. Geng, R.A. Rimmer
JLab, Newport News, Virginia, USA
E. Kako
KEK, Ibaraki, Japan

MHI have supplied several 9-cell cavities for STF (R&D of ILC project at KEK) and have been considering production method for stable quality and cost reduction, seamless dumb-bell cavity was one of them. We had fabricated a 2 cell seamless dumb-bell cavity for cost reduction and measured RF performance in collaboration with JLab, KEK and MHI. Surface treatment recipe for ILC was applied for MHI 2-cell cavity and vertical test was performed at JLab. The cavity reached Eacc=32.4MV/m after BCP and EP. Details of the result are reported.

THPP102

On Nonlinear Dynamics of a Sheet Electron Beam

emittance, plasma, electronics, brightness

1090

H.Y. Barminova
MEPhI, Moscow, Russia

In collisionless approximation the nonlinear dynamics of a charged particle beam is studied. Nonlinear oscillations of the beam radius appear due to external and self-consistent nonlinear forces. To study such oscillations the model is applied based on the kinetic distribution function dependent on the particle motion integrals. The 4th-order equation for the beam radius is obtained. The numerical solutions of the equation are analyzed. The cases of strong and weak nonlinearities caused by the own beam fields are discussed. In the case of weak deviation of the beam parameters from equilibrium ones the effective emittance growth isn't observed.

THPP103

Low Dose X-Ray Radiation Source for Angiography Based on Channeling Radiation Principle

radiation, synchrotron, optics, synchrotron-radiation

1093

T.V. Bondarenko, Yu.D. Kliuchevskaia, S.M. Polozov
MEPhI, Moscow, Russia

Angiography is one of the most reliable and contemporary procedure of the vascular system imaging. X-ray spectrums provided by all modern medical angiographs are too broad to acquire high contrast images and provide low radiation dose at the same time. The new method of narrow X-ray spectrum achieving is based on the idea of channelling radiation application. The X-ray filters used in this method allows eliminating the high energy part of the spectrum and providing dramatic dose reduction. The scheme of the facility including the X-ray filter is discussed. The results of the spectrum analysis for the channelling radiation source and typical angiography X-ray tube are discussed. Doses obtained by the water phantom and contrast of the iodine agent image are also provided for both cases.

THPP104

Simulation of the Electron Beam Dynamics in the Biperiodical Structure

simulation, coupling, Windows, impedance

1096

Yu.D. Kliuchevskaia, T.V. Bondarenko, S.M. Polozov
MEPhI, Moscow, Russia

А biperiodical accelerating structure (BAS) with operating frequency 27 GHz for the 6 MeV compact radiotherapy electron accelerator is considered. The operating frequency 27 GHz allows to significantly reduce the facility sizes, unlike the S-, X- and C-band operating linacs. The optimal geometrical parameters of BAS necessary for π/2 mode were defined by means of accelerating and coupling cell tuning. The BAS coupler was also simulated. Results of the electron beam dynamics analysis in designed structure are also discussed.

THPP112

Multipacting Optimization of a 750 MHz RF Dipole

dipole, cavity, simulation, collider

1111

A. Castilla, J.R. Delayen
ODU, Norfolk, Virginia, USA
A. Castilla
DCI-UG, León, Mexico
A. Castilla, J.R. Delayen
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Crab crossing schemes have been proposed to re-instate luminosity degradation due to crossing angles at the interaction points in next generation colliders to avoid the use of sharp bending magnets and their resulting large synchrotron radiation generation, highly undessirable in the detector region. The rf dipole has been considered for a different set of applications in several machines, both rings and linear colliders. We present in this paper a study of the effects on the multipacting levels and location depending on geometrical variations on the design for a crabbing/deflecting application in a high current (3/0.5 A), high repetition (750 MHz) electron/proton collider, as a matter to provide a comparison point for similar applications of rf dipoles.

THPP114

The SwissFEL RF Gun: Manufacturing and Proof of Precision by Field Profile Measurements

gun, cathode, coupling, vacuum

1117

U. Ellenberger, H. Blumer, M. Kleeb, L. Paly, M. Probst
Paul Scherrer Institute, Villigen PSI, Switzerland
M. Bopp, A. Citterio, H. Fitze, J.-Y. Raguin, A. Scherer, L. Stingelin
PSI, Villigen PSI, Switzerland

The high brightness electron source for SwissFEL is an in-house built 2.6 cell normal-conducting RF gun which is scaled to the RF frequency of 2'998.8 MHz. The RF gun is capable of operating at 100 Hz repetition rate and produces electron bunches at the exit of the RF gun of an energy of 7 MeV. Key features of the RF gun are described and how they have been implemented in the manufacturing process. RF field measurements of the RF gun are presented to account for the mechanical precision reached after manufacturing. The RF gun has been thoroughly tested in the SwissFEL injector test facility.

THPP115

PKU 2.45 GHz Microwave Driven H⁻ Ion Source Performance Study

ion, ion-source, operation, experiment

1120

T. Zhang, J.E. Chen, Z.Y. Guo, S.X. Peng, H.T. Ren, Y. Xu, J.F. Zhang, J. Zhao
PKU, Beijing, People's Republic of China
A.L. Zhang
University of Chinese Academy of Sciences, Beijing, People's Republic of China

Funding: This work is supported by the National Science Foundation of China (Grant Nos. 11175009, 91126004 and 11305004)
　　In a high intensity volume-produced H⁻ ion source, H⁻ ion production processes are great affected by electron temperature and gas pressure distribution within the discharge chamber. The H-/e ratio within an extracted H⁻ ion beam is much depended on the electron absorption within the extraction system. At Peking University (PKU), lots of experiments were carried out for better understanding H⁻ processes and electron dump on our 2.45 GHz microwave driven Cs-free permanent magnet volume-produced H⁻ source. Detail will be given in this paper.
Author to whom correspondence should be addressed. Electronic mail:
sxpeng@pku.edu.cn.

Poster THPP115 [2.252 MB]

THPP120

Status of Radio-Frequency (RF) Deflectors at Radiabeam

cavity, simulation, impedance, laser

1134

L. Faillace, R.B. Agustsson, J.J. Hartzell, A.Y. Murokh, S. Storms
RadiaBeam, Santa Monica, California, USA

Radiabeam Technologies recently developed an S-Band normal-conducting Radio-Frequency (NCRF) deflecting cavity for the Pohang Accelerator Laboratory (PAL) in order to perform longitudinal characterization of the sub-picosecond ultra-relativistic electron beams. The device is optimized for the 135 MeV electron beam parameters. The 1m-long PAL deflector is designed to operate at 2.856 GHz and features short filling time and femtosecond resolution. At the end of 2012, we delivered an X-band Traveling wave RF Deflector (XTD) to the ATF facility at Brookhaven National Lab. The device is optimized for the 100 MeV electron beam parameters at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory, and is scalable to higher energies. The XTD is designed to operate at 11.424 GHz, and features short filling time, femtosecond resolution, and a small footprint. The XTD is currently being assembled at ATF for high-power operation and conditioning results will be reported soon.

THPP121

Injector System for the IR-FEL at RRCAT

beam-loading, linac, FEL, cavity

1137

L. Faillace, R.B. Agustsson
RadiaBeam, Santa Monica, California, USA
A. Kumar, K.K. Pant
RRCAT, Indore (M.P.), India

An infrared (IR) free-electron laser (FEL) has been proposed to be built at the Raja Ramanna Centre for Advanced Technology (RRCAT). RadiaBeam is currently involved in the design of the RRCAT FEL's injector system. The injector will deliver an electron beam with a variable energy (from 15 up to 40 MeV) and 1.5 nC at 36.6 MHz repetition rate. We show here the beam dynamics of the beam transport through the injector as well as the RF design and mechanical model of the system.
* S. Krishnagopal et al., PRELIMINARY DESIGN OF THE PROPOSED IR-FEL IN INDIA, RRCAT, Indore, M.P. 452013, India

THPP123

Experience of Operation of the Electron Linear Accelerator Based on Parallel Coupled Accelerating Structure

cavity, controls, gun, multipactoring

1144

A.E. Levichev, A.M. Barnyakov, D.A. Nikiforov
BINP SB RAS, Novosibirsk, Russia
Y.D. Chernousov
ICKC, Novosibirsk, Russia
V. Ivannikov, I.V. Shebolaev
ICKC SB RAS, Novosibirsk, Russia

An electron linear accelerator based on parallel coupled accelerating structure was developed and produced by Budker Institute of Nuclear Physics SB RAS and Institute of Chemical Kinetics and Combustion SB RAS. Short and long versions of the accelerating structure at 2450 MHz were built. For easy disassembly electrical and vacuum connections of the first (short) structure were made using indium seals. The second structure was brazed. Now the accelerator is in operation and used to study the accelerating and RF technologies. In the report the features of the accelerator are presented, including the design and characteristics of RF antenna and solid-state switch for the electron gun. Test results of the long parallel coupled accelerating structure are discussed. Observations made on the short structure surface after it had been opened are depicted. Now the short structure undergoes certain modifications in order to accelerate higher beam currents.

THPP124

Wakefields in the Superconducting RF Cavities of LCLS-II

cavity, linac, wakefield, niobium

1147

K.L.F. Bane, T.O. Raubenheimer
SLAC, Menlo Park, California, USA
A. Romanenko, V.P. Yakovlev
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Department of Energy contract DE–AC02–76SF00515.
The superconducting cavities in the linacs of LCLS-II are designed to operate at 2K, where cooling costs are very expensive. In addition to an unavoidable static load and the dynamic load of the fundamental 1.3 GHz accelerating rf, there will be higher order mode (HOM) power deposited by the beam. Due to the very short bunch length the LCLS-II beam spectrum extends into the THz range. Ceramic absorbers, cooled to 70K and located between cryomodules, are meant to absorb much of this power; understanding their effectiveness, however, is a challenging task. In this report we calculate the amount of power radiated by the beam in the different portions of the linac as the bunch length is changed by the bunch compressors. We consider both the steady state radiation as well as transients that arise at the beginning of the linac structures. In addition, transitions due to changes in the vacuum chamber aperture at the ends of the linacs are also considered. Finally, under the assumption that all the wake power ends up in the SRF cavity walls, we estimate the wall heating and the possibility of breaking the Cooper pairs and quenching the cavities.

THPP125

Super-Compact SLED System Used in the LCLS Diagnostic System

cavity, coupling, klystron, impedance

1151

J.W. Wang, S.G. Tantawi, C. Xu
SLAC, Menlo Park, California, USA

Funding: * Work supported by Department of Energy contract DE–AC03–76SF00515.
At SLAC, we have designed and installed an X-band radio-frequency transverse deflector system at the LCLS for measurement of the time-resolved lasing effects on the electron beam and extraction of the temporal profile of the pulses in routine operations. We have designed an X-Band SLED system capable design to augment the available klystron power and to double the kick.

THPP126

Design of the High Repetition Rate Photocathode Gun for the CLARA Project

cavity, gun, simulation, multipactoring

1155

B.L. Militsyn, L.S. Cowie, P. Goudket, J.W. McKenzie, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
T.J. Jones
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
V.V. Paramonov, A.K. Skasyrskaya
RAS/INR, Moscow, Russia

The CLARA injector is required to deliver ultrashort singe electron pulses with a charge of 250 pC following with a repetition rate of 100 and/or 400 Hz. It should also provide 2 us trains of twenty 25 pC pulses with a repetition rate 100 Hz. To meet this challenge, a 1.5 cell S-band photocathode gun with a field of up to 120 MV/m and coaxial coupling has been chosen. The length of the first cell of 0.5 is decided on the basis of beam dynamic simulation with the goal to obtain optimal for CLARA parameters. In order to improve amplitude and phase stability of the RF field, the gun is equipped with RF probes, which will provide feedback to the RF system. The gun and coupler were designed to accept up to 10 MW peak and 10 kW average RF powers. Cooling will be achieved by water channels cut into the bulk of the copper. The coupler will transition from waveguide to coax using an innovative H-shaped dual feed system that cancels out any dipole mode components and allows tuning of the match. The RF and mechanical design of the CLARA high brightness photocathode gun along with beam dynamics simulations are presented in this paper.

THPP129

Carbon Field Emission Strip Cathode Electron Source

cathode, simulation, vacuum, focusing

1

T.V. Bondarenko, A.I. Botyachkova, G.G. Karpinskiy, S.A. Polikhov, G.B. Sharkov
Siemens Research Center, Moscow,, Russia
A.I. Botyachkova, G.G. Karpinskiy
National Research Nuclear University (MEPhI), Moscow, Russia
A.E. Geisler, O. Heid
Siemens AG, Erlangen, Germany

Over the recent years carbon nanostructure cathodes have become promising as a high brightness electron sources with large working area for field emission structures. Measurements and calculations of a field emission strip cathode based on carbon structure and a unit for its investigation are presented in the article. For measuring of the cathode emitting properties and determination of the electrons initial parameters used in the electron beam computer simulation the experimental setup is been developed. The setup consists of the high-voltage triode electrode system and allows to investigate the voltage-current characteristics of the cathode and to estimate the electron distribution of the beam on the anode surface. The anode electron distribution evaluations are processed by the measurements of the emitted X-ray focal spot on the anode by application of the CCD camera. Verification of the simulated electron beam dynamics can be obtained by application of the experimentally acquired data.

Poster THPP129 [4.088 MB]

THPP133

LLRF System for the CEBAF Separator Upgrade

cavity, controls, extraction, LLRF

1171

T. E. Plawski, R. Bachimanchi, C. Hovater, D.J. Seidman, M.J. Wissmann
JLab, Newport News, Virginia, USA

The Continuous Electron Beam Accelerator Facility (CEBAF) energy upgrade from 6 GeV to 12 GeV includes the installation of four new 750 MHz deflecting, normal conducting cavities in the 5th pass extraction region. This system will work together with existing 499 MHz RF Separator in order to allow simultaneous delivery of the beam to four CEBAF experimental halls. The RF system employs two digital LLRF systems controlling four cavities in a vector sum. Cavity tune information of the individual cavities is also obtained using a multiplexing scheme of the forward and reflected RF signals. In this paper we will present detailed LLRF design and current status of the CEBAF 750 MHz beam extraction system.

THPP136

Study of Femtosecond Electron Bunch Generation at t-ACTS, Tohoku University

gun, injection, bunching, radiation

1178

S. Kashiwagi, H. Hama, F. Hinode, A. Lueangaramwong, T. Muto, I. Nagasawa, S. Nagasawa, K. Nanbu, Y. Shibasaki, K. Takahashi, C. Tokoku
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
N.Y. Huang
NSRRC, Hsinchu, Taiwan

We are conducting a beam experiment of sub-picosecond electron bunch generation at a test accelerator as a coherent terahertz source (t-ACTS), Tohoku University. In the t-ACTS, the intense coherent terahertz radiation will be generated from an undulator and an isochronous accumulator ring based on the sub-picoseconds bunches. The accelerator is composed of a thermionic cathode rf gun, alpha magnet and 3 m-long accelerating structure. A velocity bunching scheme in accelerating structure is applied to generate the short electron bunch. The thermionic rf gun consists two independent cavities has been developed, which is capable of manipulating the beam longitudinal phase space. To produced femtosecond electron bunch, the longitudinal phase space distribution of the beam entering the accelerating structure is optimized by changing the rf gun parameters. The bunch length is measured by observing an optical tradition radiation with a streak camera. In the study of femtosecond electron bunch generation, a relation between the rf gun parameters and the bunch length after compression was investigated. The preliminary results of experiments will be described in this conference.

THPP139

800MeV Linear Accelerator Development for HLS Upgrade

linac, klystron, operation, injection

1189

K. Jin, Y. Hong, G. Huang, D. Jia, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Hefei Light Source (HLS) was mainly composed of an 800 MeV electron storage ring and a 200 MeV constant-impedance Linac functioning as its injector in NSRL PhaseⅠ. A new Linac has been developed successfully in view of the Full Energy Injection and the Top-up Injection scheme will be adopted in the HLS upgrade. In this paper, an 800MeV linear accelerating system construction, the constant-gradient structure with the symmetry couplers will be described in detail. The microwave system, the manufacture technology, the RF measurement, the high power testing and the accelerating system operation with beam currents are presented.

THPP140

High Transparent Matched Window for Standing Wave Linear Accelerators

linac, vacuum, network, coupling

1192

A. Leggieri, F. Di Paolo, D. Passi
Università degli Studi di Roma "Tor Vergata", Roma, Italy
A. Ciccotelli, G. Felici
S.I.T., Aprilia, Italy

This paper proposes a particular Dielectric Window (DW) for Standing Wave (SW) Linear Accelerators (LINAC’s). This study investigates the in-frequency return loss behavior of the LINAC, in order to improve matching and transmitting conditions while maintaining the optimum coupling between LINAC and High Power Microwave (HPMW) source. Device design is single-frequency based and considers the DW interface as an Input Matching Network (IMN) at the LINAC Normal Mode (NM) working frequency. Thus, design formulas are provided and Computer Aided Design (CAD) techniques are proposed. A prototype has been made and tested by performing cold S-parameter and Percentage Depth Dose (PDD) measurements of a LINAC with the proposed DW and with a traditional DW. The proposed device offers more energy transport attitude over the traditional DW, as shown by a return loss increase of 167% and an output electron energy increase of 5.5% while maintaining the same LINAC input power settings. This solution can offer a decrease of power line size, weight and cost. An after brazing global improvement of the accelerator figures of merit is also possible, as this study have demonstrated.
[1]Hiroyuki Arai, 1986
[2]K. Hirano, 1995
[3]Y. Otake, 1995
[5]A. Leggieri, 2014
[6]A. C. Ugural, 2003
[7]A. Leggieri, 2014
[8]F. Di Paolo, 2000
[9]N. Marcuvitz, 1951

FRIOA06

AWAKE: Advanced Proton Driven Plasma Wakefield Acceleration Experiment at CERN

plasma, proton, laser, experiment

1196

E. Gschwendtner
CERN, Geneva, Switzerland

Plasma wakefield acceleration is a promising alternative reaching accelerating fields a magnitude of up to 3 higher (GV/m) when compared to conventional RF acceleration. AWAKE, world’s first proton-driven plasma wakefield experiment, was launched at CERN to verify this concept. In this experiment proton bunches at 400 GeV/c will be extracted from the CERN SPS and sent to the plasma cell, where the proton beam drives the plasma wakefields and creates a large accelerating field. This large gradient of ~GV/m can be achieved by relying on the self-modulation instability (SMI) of the proton beam; when seeded by ionization through a short laser pulse, a train of micro-bunches with a period on the order of the plasma wavelength (~mm) develops, which can drive such a large amplitude wake from a long proton bunch (~12 cm). An electron beam will be injected into the plasma to probe the accelerating wakefield. The AWAKE experiment is being installed at CERN in the former CNGS facility, which must be modified to match the AWAKE requirements. First proton beam to the plasma cell is expected by end 2016.

Slides FRIOA06 [7.276 MB]